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PART I: Genetic Resources - Importance of study, genetic resources and priority species

Fruit wealth of India - S.P. Ghosh
Indian Institute of Horticultural Research and its Contribution to Indian Horticulture - I.S. Yadav
IPGRI-APO Activities On Plant Genetic Resources: Present Status and Future Plans - V. Ramanatha Rao
Genetic Resources of Native Tropical Fruits in Asia: Diversity, Distribution and IPGRI's Emphasis on their Conservation and Use - R.K. Arora
Genetic Resources and Breeding Patterns of Five Humid Tropical Fruit Tree Species - A.N. Rao and V. Ramanatha Rao

Fruit wealth of India - S.P. Ghosh


India has been exporting fresh fruits since several decades. However, in the more recent past, export promotional activities for fresh fruits have received greater attention. The fresh fruits exports which were only 27 208 tonnes in 1983-84 rose to 55 400 tonnes during 1994-95. Certain other fruits like pomegranate, sapota, banana, litchi, apple and strawberry also entered fresh fruit export market in limited quantities. India not only started exporting grapes but also produced good quality raisins and wines from grapes. During 1994, indigenous production of raisin was about 72 000 tonnes, whereas two factories in Maharashtra (Pune and Nasik) produced about 15 lakh bottles of grape wine.

In the processing sector, there are little over 4150 units registered under the Fruit Products Order (FPO) all over the country. During 1993-94, some 35 proposals for setting up 100% export oriented units were approved. Some of the joint ventures with countries like USA, UK, Germany, Netherlands and Switzerland identified banana and mango puree, fruit juice concentrates and frozen fruits as major export products.

The country is endowed with vast resources and current governmental policy is export friendly with no restrictions on export of horticultural produce. The local needs within the country is expanding at a rapid rate for fresh fruits, while for processed fruit products demand is building, particularly in the urban households. The recent economic reforms have helped in rapid expansion of certain sectors of horticultural industry through private corporate funding. Similarly, planned development in horticulture received major thrust during current 8th Five-Year Plan and several integrated developmental projects are under implementation through various central sector schemes.

Research achievements and transfer of tested technology have helped the country in attaining near self-sufficiency in many horticultural crops (Table 1). Improvement of export earnings and increased number of turnkey projects with foreign collaboration reflect the growing strength of the horticulture industry, particularly in terms of capability to compete in the global market.

Fruit Wealth

India grows almost all types of fruit crops, ranging from evergreen tropical to temperate decidous types. For the purpose of this lecture, the major tropical fruits grown in India are briefly described below.


Mango (Mangifera indica L.) is native of India. Based on the detailed study of the genus Mangifera, Mukherjee (1949, 1985) recorded that although this genus might have originated in the region covering Burma, Siam, Indo-China and Malaya peninsula, the mango itself had its birth in Assam-Burma region. The genetic diversity of mango available in India is very rich and at present more than one thousand vegetatively propagated varieties exist in the country. Clonal selection, selection from chance seedlings and breeding efforts have resulted in identification of elite improved varieties of mango for commercial cultivation in the country. In addition to large genepool of mango (M.indica) available in the country, four other related species viz. M. andamanica, M. khasiana, M. sylvatica and M. camptosperma have been reported from the country (Mukherjee 1985).

Mangifera indica germplasm in India falls under two broad categories.

a) Seedling races, both wild and cultivated types: This group consists both of monoembryonic and polyembryonic types. Most of the present day commercial varieties are selections from seedlings. A number of polyembryonic varieties have been reported mostly from the coastal areas.

b) Horticultural races - Clonal lines: Distinct clonal differences have been observed in the same variety when grown under different agroclimatic regions and propagated vegetatively from different types of parent materials and on different rootstocks. In a famous north Indian variety 'Dashehari', more than 50 types have been under study at the Central Institute of Sub-tropical Horticulture (CISTH), located in Lucknow, U.P. Improved clones of commercial varieties like Dashehari, Langra and Himsagar have already been made.

Table 1. Area, production and productivity 6f fruits during 1994-1995

Sl. No.

Name of Crop

Area (ha)

Production (mt)

Productivity (mt ha-1)




















































Others (including coconut)







Source: NHB Production Yearbook 1997. National Horticulture Board, Ministry of Agriculture, Govt. of India, New Delhi, March 1997.
The genepools of mango available in the country have largely been evaluated and from systematic studies the horticulturally important characters like dwarfness, regularity of bearing, season of cropping, fruit characters (size, colour, quality), and resistance to pests and diseases have been located. The identified donor sources have been employed in breeding programmes, which have resulted in release of a number of mango hybrids in the country. Details of the cultivars identified for various important traits/characters as compiled by Chadha and Yadav (1997) are given in Table 2.

Table 2. Cultivars identified for desirable traits




Creeping, Latra, Jerala Dwarf, Rumani, Neelum (north India), Kalapadi (north India), Manjeera, Mahmooda Vikarabad, Arka Aruna, Amrapali (north India)

Sex ratio

Dashehari, Langra, Neelum, Amrapalli, Alphonso, Rajapuri

Self- incompatibility

Dashehari, Langra, Chausa, Himsagar

Fruit size

Banganpalli, Janardhan Pasand, Kensington, Fazli, Langra, Mulgoa.

Skin colour

Janardhan Pasand, Sindhura, Benazir, Fernandin, Suvarna Rekha, Vanraj, Rosa, Kensington, Tommy Atkins, Sensation, Irwin, Arka Puneet, Nazuk Badan, Raspuri

Pulp content

Langra, Dashehari, Pairi, Arka Aruna, Sindhu, Sahib Pasand, Amrapali, Sunderja, Mallika, Bhutto Bombay, Fazli, Khudadad, Chausa, Sora, Vanraj

TSS content

Sahib Pasand, Doodh Peda, Dashehari, Langra, Arka Puneet, Mallika, Lazzat Baksh, Amrapali, Sakkar China, Gopal Bhog, Rani Pasand, Sunderja

Keeping quality

Alphonso, Totapuri, Sunderja, Dashehari, Banganpalli, Kesar, Rataul, Arka Anmol, Arka Puneet

Regular bearing

Neelum, Kalapadi, Totapuri, Arka Anmol, Kesar

Maturity period



Mithwa, Zardalu, Lazzat Baksh, Guruvarm, Chandrakaran, Panakalu, Velai Kolumban


Kaitki, Bathui, Fazli, Neelum, Arka Anmol, Chausa, Fakhr-us-Samar, Puttu, Sora, Sultan-us-Samar, Azam-us-Samar

Processing (pulp/juice/nectar)

Alphonso, Rani Pasand, Sahib Pasand, Padiri, Banganpalli, Totapuri, Hyder Saheb, Pedda Rasam, Sukul, Allumpur Baneshan, Neelum, Chausa, Alif Laila, Prabha Shankar, Kesar, Arka Anmol, Arka Puneet

Canned slices

Dashehari, Baneshan, Gundu, Khader, Langra, Bombay Green, Chausa, Safeda

Pickle and chutney

Amlette, Chandrakaran, Karania, Ram Kela and other mango varieties at unripe stage

Although evaluation reports are available for reaction of cultivars to insects and diseases in fields, no donor sources of resistance have yet been identified.

Through clonal selections, high TSS containing varieties (Sahib Pasand, Lakshman Bhog), regular bearing Dashehari (clone No.53), off-season selection (Niranjan), heavy bearing Langra (about 780 kg/plant), dwarf selections of south Indian varieties Rumani and Totapuri and dwarf polyembryonic types (Manipur I and Manipur II) have been identified as promising ones.

Varietal diversity

In India, about 30 commercial varieties are grown on large scale and there is a distinct consumer preference of varieties in different regions. Isozyme studies revealed that north Indian varieties differ genetically from south Indian varieties. Some of the prominent commercial varieties in different regions of India are:

i) Northern India - Dashehari, Langra, Bombay Green, Chausa, Fazli.
ii) Central India - Langra, Dashehari, Chausa, Safeda and Sunderja.
iii) Western India - Alphonso, Kesar, Mankurad, Vanraj.
iv) Southern India - Banganpalli, Totapuri, Neelum, Pairi, Mulgoa, Kalepad, Rumani.
v) Eastern India - Langra, Kishan Bhog, Zardalu, Fazli, Himsagar, Bombai, Malda.
Some of the quality parameters of a few commercial varieties of India are given in Table 3.

Table 3. Variation in fruit quality of mango


Fruit weight (g)

Pulp (%)

TSS (Brix)









Bombay Green













































In India, banana is cultivated in 444.4 thousand ha with a total production of 11.83 million tonnes, contributing 31% of the total fruit production. A total of 565 accessions of banana are maintained in field genebank at the NRC for Banana. The collections continued to be maintained at the Indian Institute of Horticultural Research (IIHR), Bangalore (241), TNAU, Coimbatore (125), Banana Research Station, Kannara (190), Central Horticultural Experiment Station, Hajipur (115), and Gujarat Agricultural University Research Station, Kowur (51). Banana cultivars grown in different regions of the country are shown in Table 4.

Table 4. Banana cultivars grown in different regions in India



Andhra Pradesh

Dwarf Cavendish (AAA), Robusta (AAA), Amritpani (Rasthali, AAB), Thella Chakkrakeli (AAA), Karpoora Chakrakeli (Poovan AAB)


Jahaji (AAA), Dwarf Cavendish, Bor-Jahaji (AAA, Robusta), Malbhog (AAB), Chinia (AAB), Manohar (ABB), Kanchkol (AAB), Chini Champa (AB), Bhimkol (AAB)


Dwarf Cavendish (AAA), Alpan (AAB), Chini Champa (AB), Malbhog (AAB), Muthia (ABB), Kothia (ABB), Monthan (ABB)


Dwarf Cavendish (AAA), Lacatan (AAA), Harichal (Lokhandi, AAA)


Dwarf Cavendish (AAA), Robusta(AAA), Poovan(AAB), Rasabale (AAB, Rasthali), Hill Banana(AAB), Monthan (ABB), Elakki Bale (AB)


Nendran (AAB Plantain), Palayakodan (Rasthali), Dwarf Cavendish (AAA), Robusta (AAA), Monthan (ABB), Red Banana(AAA)


Basrai (Dwarf Cavendish), Robusta(AAA), Lal Velchi (AAB), Safed Velchi (AB), Safed Velchi(AB), Rajeli (AAB, Nendran), Clones of Basrai

Tamil Nadu

Virupakshi (AAB), CO 1 (AAB), Robusta(AAB), Dwarf Cavendish (AAA), Red Banana (AAA), Poovan (AAB), Rasthali(AAB), Nendran (AAB), Monthan (ABB)

West Bengal & Orissa

Champa (AAB), Morthaban (AAB, Rasthali), Amrit Sagar (AAB), Giant Grover (AAA), Lacatan (AAA), Monthan (ABB)


Out of 48 species of the genus Carica, edible fruits are obtained only from Carica papaya. In about 6 species, resistance for different biotic and abiotic stresses have been utilized in crop improvement programmes. Virus resistant C.cauliflora and cold hardy C.candamarcensis and C. pentagona have been collected and extensively used in breeding programme at ICAR institutes.

Systematic germplasm collection and evaluation work was carried out in 1965 at the Regional Station, IARI, Pusa (Bihar). Studies on more than 100 germplasm lines of papaya showed that papaya exhibits variability in respect of plant height (1 to 2.5 m), plant vigour (dwarf to vigorous), plant colour (purple to whitish green), flower type (staminate to pistillate), fruit shape (long to round), fruit size (5 to 30 cm diameter), fruit weight (0.090-13.0 kg), fruit number (10-80), skin colour (golden yellow to dark green), flesh colour (pale yellow to blood red), taste (bitter to very sweet), flavour (objectionable odour when overripe - brown to black). Further progeny row plot trials helped in identifying different desirable parental lines useful for breeding programme. The component characters, viz., leaf length, earliness in fruiting, number of nodes to first flowering, single fruit weight and height of plants were found to be important for expression of genetic diversity.

Varietal improvement

Till date, 15 high-yielding varieties of papaya have been developed in the country, out of which 9 are widely adopted. A few successful hybrids have been developed and heterosis noticed with a wide range of breeding materials. Some of the improved varieties are given here.

Coorg Honey Dew: It is a selection from the variety 'Honey Dew' and is a popular gynodioecious cultivar which bears oblong-shaped fruits with thick flesh and good flavour. The variety can be maintained pure by growing in isolation.

Pusa Dwarf: It is a delicious variety with dwarf plants and medium-sized (1-2 kg) oval fruits. The plant starts bearing from 25 to 30 cm above ground level and is comparatively drought hardy. This variety is very suitable for high-density planting.

Pusa Giant: Plants are vigorous, sturdy and tolerant to strong wind. It is a dioecious cultivar with big-sized (2.5-3 kg) fruits, suitable for canning industry.

Pusa Majesty: A gynodioecious line, tolerant to viral diseases and root-knot nematodes. The variety is suitable for papain production and is comparable to CO.2 for papain yield. Fruits are medium-sized, round in shape and have good keeping quality.

Pusa Delicious: This is a gynodioecious line with medium-tall plants, and has heavy yield and good qulity fruits (10° - 13° Brix). The fruits are medium-sized with deep orange flesh with excellent flavour.

CO. 1: The variety is evolved by sibmating the type 'Ranchi' over 8 years. It is a dwarf plant, producing the first fruit within 60-75 cm from the ground level. Fruit is medium-sized, spherical, has smooth greenish-yellow skin, nipple slightly ridged at the apex, flesh orange-yellow, soft, firm. It is moderately juicy with good keeping quality. The objectionable papain odour is practically absent in the fruits.

CO. 2: It is a selection purified from a local type at Agricultural College and Research Institute, Coimbatore. Fruits are medium-sized, obovate, greenish yellow, ridged at the apex, flesh red in colour, soft to firm, moderately juicy with good keeping quality. It is a suitable type for extraction of papain. It gives 4-6 g dried papain/fruit.

CO. 3: The fruit of this hybrid (CO.2 x Sun Rise Solo) is larger in size when compared with Solo and exhibits all the desirable attributes of Solo. Total soluble solids (TSS) is as high as 13.8° Brix and average fruits weight ranges from 835 g to 1.5 kg. It has hermaphrodite character and thereby the cost of cultivation is reduced. The sex ratio of this hybrid is 55 female: 45 hermaphrodite flowers. Each tree gives 100 to 120 fruits during the bearing period of 2 years.

CO. 4: This is a hybrid of CO. 1 x Washington. The fruits is medium-sized with round shape similar to Co. 3. Fruit flesh is thick and yellow with purple tinge. Tree has attactive colouration in all parts of the plant and is suitable for home gardens. Mean fruit weight is 1.3 to 12.5 kg. Each tree gives 80 fruits over a period of 2 years. The quality of the fruits is bettter than CO. 1 and Washington, with a TSS content of 13° Brix.

CO. 5: It is a selection from Washington and isolated for its high papain production which has high proteolytic activity and 72.2% protein. It produces consistently 14-15 g dry papain/fruit. It gives 75-80 fruits/tree in 2 years with an average yield of 1100-1600 kg dried papain/ha.

CO. 6: It is a selection from variety Giant. Trees are medium-statured. Fruit shape is round with yellow flesh. Mean fruit weight is 2-3 kg and it is suitable for table purpose as well as for latex extraction, but the quality of latex is relatively poor. It yields 80-100 fruits/tree in 2 years.

At the IIHR, Hessarghatta, 2 gynodioecous hybrids, viz., 39 and 54, developed from crosses of Sunrise Solo x Pink Flesh Sweet and Waimanalo × Pink Flesh Sweet have been found promising with high TSS (14.5° Brix) and better shelf-life. A dwarf mutant Pusa Nanha with prolific fruiting habit has been developed by treating papaya seeds with 15 kr gamma-rays. This variety is most suitable for high density orcharding and for kitchen gardens.


Most of the species under the genus Citrus are native to tropical and subtropical regions of Asia, particularly, India, China and in the region between these two countries. The north-eastern region of India is considered as one of the natural home of Citrus, at least for a few species. Certain non-edible species like Citrus indica, C. ichangensis, C. macroptera and C. latipes are found growing in wild and semi-wild state in the northeastern region. Bhattacharya and Dutta (1956) considered them as indigenous to the area. Also different strains of citron (C. medica), sour pummelo (C. megalaxycarpa), rough lemon (C. jambhiri) and sour orange (C. aurantium) have been found to grow in north-eastern India. It is possible that since very early days, different citrus species might have been distributed in the geographically contiguous regions which are natural home of citrus diversity, particularly between China and India.

Table 5. Commercially important citrus fruits of India




Mandarin (Citrus reticulata Blanco)

Nagpur mandarin, Khasi mandarin, Coorg mandarin, Kamala orange, Darjeeling mandarin, Kinnow

Commercially grown in Maharashtra, Karnataka, Tamil Nadu, Madhya Pradesh, Punjab, Rajasthan, Assam, Sikkim, West Bengal, Meghalaya

Sweet Orange (C. sinensis Osbeck.)

Mosambi, Sathgudi, Blood Red Malta, Hamin Pineapple, Valencia and Jaffa

Commercially grown in Deccan Plateau, Punjab, Andhra Pradesh, Tamil Nadu

Acid Lime (C. aurantifolia Swing.)

Kagzi lime, Vikram, Pramalini and PKM-1, Baramasi, Kagzi Seedless lime (C. latifolia Tan.)

Commercially grown in Andhra Pradesh, Maharashtra, Gujarat, Bihar, Karnataka and Tamil Nadu

Lemon (C. limon Burm. f.)

Baramasia, Assam lemon, Pant lemon, Gandhraj, Seville lemon, Nepali Oblong, Nepali lemon, Italian lemon, Eureka lemon

All over the country in homestead gardens

Grapefruit (C. paradisi Macf.)

Dancan, Marsh Seedless, Ruby

Limited in cultivation

Pummelo (C. grandis Osbeck.)

Chakotra, Gagar and local selections

Limited in cultivation

Belladikithuli (C. madaraspatana Tanak

Valadipudi, Kichli, Belladikithuli a)

Commercial orchards in Guntur in Andhra Pradesh

Mandarin orange is concentrated in Maharashtra state (especially Nagpur, Amaravati, Wardha and Yevatmal districts) and in the north-eastern region of India (states like Assam, Arunachal Pradesh, Meghalaya, etc.). In the Brahmaputra valley of Assam, particularly in the Tinsukia- Dibrugarh region, excellent quality oranges are produced.

Limited area of Karnataka (Coorg), Tamil Nadu (Nilgiri, Palani and Shevory Hills) and Kerala (Wynad) states in the south are also covered under mandarins. Satpura Hills of Madhya Pradesh, adjoining Vidarbha region of Maharashtra also grow good quality mandarins. Of late, Kinnow orange, a hybrid of King x Willow Leaf mandarin has spread to a great extent in the north-western India, especially in Punjab, parts of Himachal Pradesh, Uttar Pradesh and Rajasthan where it occupies about 27 thousand ha. In Punjab state alone, about 18 000 ha were covered under Kinnow upto 1989 and it is proposed to cover 25 000 ha by 2000 A.D. In the foothills of Himachal Pradesh, parts of Rajasthan, Maharashtra, Tamil Nadu and Karnataka states also, Kinnow is being grown on commercial scale. Under semi-arid irrigated areas, kinnow comes up well. In Nagpur and Akola in Maharashtra, it performed very well. Kinnow is, however, not successful in tropical parts of south India.

Sweet oranges are adapted well to arid tropics and subtropics. Sweet oranges are commercially grown in Andhra Pradesh, Maharashtra, Punjab, and parts of Tamil Nadu, Rajasthan and Uttar Pradesh. Sweet orange cultivar in Andhra Pradesh is Sathgudi, which is akin to Batavia orange. In western and central India sweet orange cultivar Mosambi is predominant, whereas in the north-western India, Malta, Jaffa and Valencia are important varieties.

Acid lime is grown on commercial scale in Tamil Nadu, Andhra Pradesh, Maharashtra and Karnataka states. In Andhra Pradesh alone, about 27 000 ha is covered under acid lime. Lemons are grown commercially only on a limited scale. Eureka lemon had been found to be promising but has not spread well. In northeastern India, a lemon-citron type known as 'Assam Lemon' is popular and has found favour in homestead gardens. The commercially important citrus fruits of India with the names of important cultivars and their distribution are mentioned in Table 5 based on Singh and Chadha (1993).


Grape is grown in 42 139 ha with 672.9 thousand tonnes of production. Most of the commercial varieties are introductions from abroad. Two wild species, namely, Vitis lanata and V. riparia are reported from north-western Himalayan foothills. The commercial varieties are both seeded and seedless types.

Seeded Cultivars

Anab-e-Shahi: The origin of this cultivar seems to be a bud sport as it has a satelite chromosome. It has been one of the most productive cultivar grown in India and yielded over 12-16 tonnes/ha/year. It has attractive large bunch of berries with good shipping quality.

Bangalore Blue: It is reported to be a vinifera × labrusca hybrid. It is medium in vigour and yield. The bunches are small and compact. The berries are small to medium and dark blackish purple in colour. The ripening is uniform. Apart from being used for table purpose, it is being extensively used for juice and wine making. It is known for its hardiness and resistance to disease for which it finds a suitable place as parent in a breeding programme aimed at inducing disease resistance.

Black Champa: It is a selection made at the Indian Institute of Horticultural Research (IIHR), Bangalore. The vines are vigorous with medium yielding capacity. The seeded grape of excellent quality is suitable for table juice and red dessert wine. It is susceptible to cracking and rotting during rains.

Cheema Sahebi: A selection from open pollinated seedlings of "Pandhari Sahebi' in India. The vine is vigorous and a very heavy yielder. Bunches are long, conical and shouldered with medium-sized, oval and pale berries. Shipping quality is poor due to weak pedicellar attachment. It is a late-ripening cultivar.

Gulabi: It is also known as Karachi, Paneer Drakshi and Muscat. It resembles Muscat Hamburg of Australia. The vine is medium in vigour and yield; bunches are small and loose with deep purple, small and spherical berries. It has thick-skinned berries which attribute to good keeping quality. It has a muscat flavour. The ripening is early and fairly uniform.

Seedless Cultivars

Perlette: Berries are medium in size, whitish green and spherical. Flesh is soft and mild muscat flavoured. It has good keeping quality. Small underdeveloped berries (shot berries) scattered all over the bunch is a major defect.

Pusa Seedless: It is a selection made at the Indian Agricultural Research Institute, New Delhi from unknown origin. It resembles Thompson Seedless in many characters. Vine is vigorous and medium yielder. Apart from table purpose, good quality raisin can also be prepared from it. It has good keeping quality.

Thompson Seedless: It is one of the most commercially important variety in India. It is a table and a raisin cultivar. It has wide adaptability and has performed well in all the grape growing regions of the country. It is mid-season and uniform in ripening. Vine is medium in vigour, the bunch is medium-large, long, conical to cylindrical, shouldered and compact. The berries are yellowish green to golden yellow when fully ripe, small and elongated. Eating and keeping quality are excellent. Berry size is improved through GA application.

Table 6. Composition of some underutilized fruits in India






Custard apple































Total sugar






Vitamins (mg/100g)

(Vit. C)

(Vit. C)

540 IU
(Vit. A)

931 IU
(Vit. A)

(Vit. C)

Arkavati: It is a hybrid developed at IIHR, Bangalore. It is a high yielding variety, suitable for raisin making.

IIHR also released other varieties like Arka Kanchan (seeded), Arka Shyam, Arka Hans, Arka Neelmani (black seedless), Arka Shweta (white seedless). One black hybrid Arka Krishna has been released for juice making, while Arka Soma and Arka Trishna are good for wine preparation.

Underutilized Tropical Fruits

The underutilized fruits like Jujube or ber (Ziziphus mauritiana), aonla or Indian gooseberry (Emblica officinalis), jackfruit (Artocarpus heterophyllus), bael (Aegle marmelos), custard apple (Annona squamosa), jamun (Syzygium cuminii), karonda (Carissa congesta), tamarind (Tamarindus indica) are spread over the tropical and subtropical belts of the country. Some of these have good nutritive value and considerable local demand (Pareek and Sharma 1993). The chemical composition of the fruits is shown in Table 6, while Table 7 gives the germplasm availability in India.

Table 7. Germplasm accessions of underutilized fruits maintained in India



Commercial Varieties

Ber (Ziziphus spp.)


Umran, Banarsi Karaka, Gola, Seb

Aonla (Emblica officinalis)


Banarsi, Chakaiya, Krishna, Kanchan, NA-7, NA-8, NA-10

Custard apple (Annona sp.)


Balanagar, Mammoth, Arka, Arka Sahan

Bael (Aegle marmelos)


Kaghji Gonda, NB-5, NB-9

Jackfruit (Artocarpus heterophyllus)


Gulabi, Hazari, Rudrakshi, Muttam Varikka

Ber (Ziziphus mauritiana)

Indian ber or jujube belongs to the genus Ziziphus of the Rhamnaceae family. Out of about 50 species of the genus, about 20 occur in India. It is the hardiest cultivated fruit tree grown in north Indian Plains. In the arid Rajasthan state, about 750 ha area was under the crop in 1991. Indian ber starts vegetative growth with commencement of rainy season and sheds its leaves during summer. For good cropping, pruning is essential. Presently, about 70 000 ha is covered under ber in the country.

Cultivar Umran has high yield potential with large sized fruits (av. weight 26.8g), whereas cv. Gola, Reshmi, Illaichi have distinct quality attributes. Gola is highly drought hardy. Unlike Chinese cultivars, Indian ber cultivars are not very tolerant to low temperature. Some cultivars, namely, Safed Rohtak, Sanaur 5, Jhajja Selection and Katha Phal showed resistance to powdery mildew, which is the major disease in ber.

The Ziziphus species commonly used in India, with their distribution and use are given in Table 8 while Table 9 describes some promising characteristics of important ber cultivars.

Aonla (Emblica officinalis)

This belongs to the family Euphorbiaceae and is said to be indigenous to tropical South Asia, particularly central and southern India. Aonla tree is hardy and seedling trees can even attain a height of about 20 metres. It prefers sandy loam soil but can be grown in a variety of soils including alkaline soils.

Table 8. Ziziphus species of common use in India



Economic use

Z. mauritiana

Maharashtra, Punjab, U.P., Bihar, Rajasthan

Edible fruit, bark for tannin, leaf for fodder

Z. nummularia (syn. Z. rotundifolia)

North-west India, A.P.

Edible fruit, bark for tannin

Z. rugosa

U.P., Bihar, M.P.

Edible fruit

Z. sativa

Punjab, Bengal

Edible fruit

Z. xylopyrus


Host for lac

Wide range of variability in the germplasm is noticed. It is commercially cultivated in Pratapgarh, Varanasi, Azamgarh and other districts of U.P., and a number of promising selections have been made. The improved cultivar NA - 7 is a selection from the seedling population of the cultivar Francis. Aonla fruits are one of the richest sources of natural ascorbic acid. The fruit is widely used in the Indian system of medicine.

Table 9. Characteristics of improved commercial cultivars of ber/Indian jujube


Fruit character




Large, golden yellow to light chocolate skin, oval fruit, TSS-19%, acidity-0.2%

150-200 kg/ tree

Susceptible to powdery mildew


Medium sized, round, golden yellow fruits TSS-20%

40-60 kg/tree at 5th year under rainfed and about 100 kg under irrigation

Early variety suitable for rainfed condition


Medium sized apple shaped, greenish yellow skin fruits, TSS-17.5%

Similar to cv. Gola

Mid-season variety with upright growth


Very small sized (6-7g/fruit) round fruits of golden colour, turning chocolate

100 kg/tree

Almost seedless, flavoured fruits, small tree canopy brown on ripening

Bael (Aegle marmelos)

Bael belongs to family Rutaceae and is an indigenous fruit of India. The trifoliate aromatic leaves are used for sacred offering in Hindu religious functions. It is reported to have medicinal value; the unripe fruit is often prescribed for diarrhoea and dysentry, while ripe fruit is a tonic, laxative and good for heart. Fruit is a rich source of carotene and riboflavin. There was no standard cultivar in bael. In the recent past, some improved cultivars (NB-1, NB-7, NB-9) have been identified. A large genetic diversity still remains unexplored.

Jackfruit (Artocarpus heterophyllus)

Jackfruit grows wild in the forests of Western and Eastern Ghats of India and a few species, namely, A.chaplasha, A.hirsutus and A.lakoocha are available in nature in Assam, West Bengal in the Eastern India and in the Andaman Islands. Being a cross pollinated plant, propagated mainly by seeds, a wide range of variability is noticed in Jackfruit. There are two broad groups, soft flesh and firm flesh types. The soft flesh types are quite juicy and pulp is highly scented. So far there is no well defined variety, and in different localities, local varieties are known differently. Local selections have been named as Gulabi (rose scented), Champa (flavour like that of Michelia sp.), Hazari (bearing large number of fruits in a tree).

As a result of local survey, some better types have been collected. Since in India raw jackfruits have good demand as vegetable for culinary purpose, emphasis is also given on fruit characters like thinner rind and soft flesh at premature stage of fruit development. A few selections, namely, NJT1, NJT2, NJT3 and NJT4 with large fruits and excellent pulp quality have been identified for table purpose, while types like NJC1, NHC2, NJC3 and NJC4 were found to be better for culinary purpose. North-Eastern region of India produces large quantity of Jackfruit. The state Assam of in eastern India is reported to have about 8000 ha under Jackfruit, while Tamil Nadu state in south India has a covered area of about 2960 ha under this crop.

Jamun (Syzygium cuminii)

Jamun belongs to the family Myrtaceae and is a native of India, Burma (Myanmar) and Sri Lanka. The tall tree with evergreen foliage is an excellent roadside tree and very often used as windbreaker. It is widely grown both in north and south India. Distribution of some economic species of Syzygium has been shown in Table 10. Small dark purple coloured fruits with sub-acid spicy flavour are eaten fresh.

There is no standard variety in jamun. In north India, a type known as 'Ra Jamun' with big (2-5 cm long fruits) fruits is normally grown. A small (1.5-2.0 cm long and 1-1.5 cm diameter) fruited type is also grown for late harvesting. A wide range of variability exists in jamun and survey conducted (Keskar et al. 1989) in Pune and Ahmednagar districts in Maharashtra state revealed wide variation in fruit weight (3.5 to 16.5 g), pulp contents (54-85 %), TSS (4.5-17 %) and acidity (0.16 to 0.55 %). Some promising lines have been selected.

Table 10. Syzygium species of horticultural interest found in India



S. cuminii

Indo-Gangetic plains of north India, Tamil Nadu in south, widely distributed

S. arnottianum

Western Ghats, the Nilgiris, Palni and Anamalai Hills

S. bracteatum

Western Ghats, Eastern/north-eastern India

S. operculatum

Grows wild in Nilgiri Hills of Tamil Nadu, Western Ghats

S. aqueum

Mainly in Assam, Sikkim and Meghalaya, Eastern/ north-eastern India

S. fruiticosum

Grows as an avenue tree, widely distributed

Other Fruits

India grows many other tropical fruit crops. Fruits like guava, litchi, sapota, pomegranate and pineapple are grown commercially. Good germplasm exists in these crops and improved cultivars have been released. In custard apple, a few promising cultivars have been identified. At the IIHR, large number of hybrids obtained from different crosses are being evaluated. In passion fruit, a cultivar named, 'Kaveri' with multiple resistance against Fusarium sp. leaf spot disease and nematodes has been developed from crosses of Passiflora edulis × P. edulis f. flavicarpa. In sapota, Kalipatti, Cricket Ball and Kirtibarthi are some popular cultivars, while in guava, Allahabad Sufeda and L-49 are popular. In pomegranate, very fast expansion has taken place and some excellent, high yielding cultivars like 'Ganesh' G-137 have been released. In a traditional crop like tamarind, several high yielding types have been selected. Tamil Nadu state alone covers about 13 820 ha under tamarind and produces about 42 000 tonnes of fruit.


The fruit industry in India has made remarkable progress during the last three decades. The area under fruits has increased from 1.22 million ha in 1961 to 5.56 million ha in 1994-95. As per FAO Yearbook 1994, India ranked second after China with a production of about 33.23 million tonnes. Our share in the world production of fruits is about 8% and India produces about 65% of the world mangoes and 11% of the world bananas, ranking first in both the crops. Although banana occupies less than 12% of the area under fruits, it contributes nearly 32% of the total fruit production in the country. Quantity-wise, out of all fruits produced in the country, maximum production is in banana (32%). The five fruits, mango, banana, citrus, guava and apple, cover about 75% of the total fruits produced in the country. In less known fruits like sapota, jujube/ber, aonla and pomegranate, area expansion and production rise during the recent years is simply spectacular.


Bhattacharya, S.C. and S. Dutta. 1956. Classification of Citrus Fruits of Assam. ICAR Monogr. No. 25.

Chadha, K.L. and I.S. Yadav 1997. Mango. Pp. 419-432 in 50 Years of Crop Science Research in India, ICAR, New Delhi.

Kesar, E.G., A.R. Karale, B.C. Dhanigle and K.G. Choudhari. 1989. Improvement of jamun (Syzygium cuminii Sk.) by selection. Mah. J. Hort. 4:117-120.

Mukherjee, S.K. 1949. A monograph of the genus Mangifera L. Lloydia 12:73-136.

Mukherjee, S.K. 1985. Systematic and ecogeographic studies in crop genepools: 1. Mangifera L. IBPGR, Rome, Italy. 86 p.

Pareek, O.P. and S. Sharma. 1993. Genetic resources of underexploited fruits. Pp. 189-241 in Advances in Horticulture - Fruit Crops (K.L. Chadha and O.P. Pareek, eds.). Malhotra Publishing House, New Delhi.

Singh, H.P. and K.L. Chadha. 1993; Genetic resources of citrus. Pp. 95-122 in Advances in Horticulture - Fruit Crops (K.L. Chadha and O.P. Pareek, eds.). Malhotra Publishing House, New Delhi.

Indian Institute of Horticultural Research and its Contribution to Indian Horticulture - I.S. Yadav


The Indian Institute of Horticultural Research (IIHR) was established by the Indian Council of Agricultural Research (ICAR) towards the end of fourth five-year plan. It started operating in New Delhi on 5 September 1967 and was subsequently shifted to Bangalore on 1 February 1968 at Hessaraghatta where a Fruit Research Station was started as early as February 1938 by the Imperial Council of Agricultural Research, which in due course was converted into National Hortorium, located 26 km north of Bangalore on the Bangalore - Bombay line. IIHR was the first of its kind in the country mandated specifically to horticultural crops. Initially, 24.7 ha land under the National Hortorium was transferred and later on Government of Karnataka gave 238 ha. land in the village Ivarakandapura opposite the National Hortorium. The Institute started with a skeletal staff with 7 research divisions manned by 50 scientific and technical staff in various disciplines. Over the years, the Institute has grown up in its size and sphere of activities and now is one of the pre-eminent horticultural research institutes in Asia. Today, the Institute has completed 28 years of service to horticultural research and development.


The Institute is well set to work with the following mandate:

1. To undertake basic and applied research for developing strategies to enhance productivity and utilization of tropical horticultural crops, viz., fruits, vegetables, ornamentals, medicinal and aromatic plants and mushrooms.

2. To act as a repository of scientific information relevant to horticulture.

3. To act as a centre for training for upgrading of scientific manpower in modern technologies for horticultural production.

4. To collaborate with relevant national and international agencies in achieving the above objectives.

Set-up and Activities

The main experimental farm established at Bangalore has a total area of 266 ha which is divided into 9 blocks working on various horticultural crops, viz., fruits, vegetables, ornamental, and medicinal and aromatic crops including mushrooms with 10 full fledged divisions and 4 sections apart from two units of All India Coordinated Projects on Tropical Fruits and Betelvine with well equipped laboratories. In addition, the Institute is also involved in All India Coordinated Research work on specific problems carried out with international collaborations and bilateral agreements with other countries. The Institute is also involved in Post-graduate education and training in collaboration with the University of Agricultural Sciences, Bangalore, and Dharwad and Birsa Agricultural University, Ranchi. Many of the scientists are recognized as guides for the University students.

Presently, the Institute has got four experimental stations, viz., Central Horticultural Experiment Station, Chettalli; Central Horticultural Experiment Station, Godhra; Central Horticultural Experiment Station, Ranchi and Central Horticultural Experiment Station, Bhubaneshwar which take care of research needs of various states and adjoining areas. The research needs of tribal belts of eastern and western region of the country are also taken care of by these centres and Krishi Vigyan Kendra at Gonikoppal, Karnataka. The Institute is headed by a Director, supported by scientific and technical staff, administration, accounts and other supporting staff, which now number over 700.

Significant Achievements

Crop Improvement

Germplasm collecting, maintenance and conservation

Field germplasm collections: Valuable germplasm of fruits, vegetables, ornamentals, medicinal and aromatic crops have been collected within the country as well as introduced from abroad through the National Bureau of Plant Genetic Resources, New Delhi. The number of collections presently available at the Institute are - fruits: 1669, vegetables: 5509, ornamentals: 1092, and medicinal and aromatic crops: 80 (Table 1). These germplasms are being maintained in field by the breeders and are used for breeding programmes.

Table 1. Germplasm of horticultural crops available at IIHR

Name of the crop

No. of accessions


1. Mango


2. Banana


3. Grape


4. Citrus rootstocks


5. Limes and lemons


6. Guava


7. Pomegranate


8. Fig


9. Jujube


10. Apple


11. Kiwi


12. Others


13. Watermelon


14. Muskmelon



1 669


1. Amaranthus


2. Bitter gourd


3. Cabbage


4. Bottle gourd


5. Brinjal


6. Brocoli


7. Chillies

1 000

8. Carrot


9. Cauliflower


10. Chinese cabbage


11. Cowpea


12. Cucumber


13. Dolichos


14. French bean


15. Okra


16. Onion


17. Palak/spinach


18. Sponge gourd


19. Pumpkin


20. Ridge gourd


21. Sweet pepper


22. Tomato

1 200

23. Garden peas



5 509


1. Bougainvillea


2. Roses


3. Gladiolus


4. Chrysanthemum


5. China aster


6. Hippeastrum


7. Hemerocallis


8. Orchids



1 092

Medicinal and Aromatic Crops

1. Catharanthus roseus


2. Dioscorea


3. Jasmine


4. Patchouli


5. Pogostemon


6. Scented geranium


7. Solanum spp.




Grand total

8 350

Exotic germplasm: Based on requisitions received from the scientists of the Institute, following exotic germplasm was introduced during 1990-95.


Taiwan AVRDC


Other countries











Genebank: The Institute has established a genebank to conserve horticultural germplasm for short, medium and long term periods. It has a number of cold chambers with temperature varying from +25°C to -20°C. The seed is processed, packed in suitable containers and stored at temperatures according to the requirement of each crop. The genetic information as well as placement of germplasm in racks in cold chambers have been computerized for quick display and retrieval. The IIHR genebank has a capacity to hold more than 200 000 accessions, so far about 2500 accessions have been stored (Table 2).

Table 2. Cropwise number of accessions stored in genebank at -20°C


Name of crop

No. of accessions



















1 317


Cluster bean






China aster



Garden peas






Ridge gourd



Solanum sp.






2 376

Grand total

2 496

Seed storage. Research has been in progress to enhance seed longevity in fruits, vegetables and ornamentals by manipulating pre-harvest factors, moisture content, temperature, oxygen etc. Studies have also been carried out on genetic stability, change in physiological and biochemical parameters in stored seed germplasm.

Among fruits, seeds of papaya, lemon, kagzi lime, mandarin, citrus rootstocks, ber/jujube, mango and phalsa have been studied for their storage qualities. Papaya seeds were found viable for short periods (6 months) under ambient conditions, but their longevity was extended to four years when stored with silica gel, which increased further by storage at 10°C. Leaching of soluble sugars and free amino acids was found to increase and dehydrogenase activity decreased due to ageing of seeds.

Seed viability of kagzi lime was retained for 5 years when stored in polyethylene and aluminium foil laminated bags at 5°C or -18°C with imbibed storage at 5°C. Storage of fruits at 5°C or - 15°C was also found to preserve viability for 120 days. Seed drying was found to reduce germination of seeds of different citrus rootstocks. In Coorg mandarin, seed was found to lose viability rapidly under ambient conditions, and none germinated after 30 days. This was accompanied by increased leaching of soluble sugars, amino acids and decreased dehydrogenase activity in seeds. In ber, the seed viability was lost rapidly under ambient conditions while it was retained for 4 years at 5°C and -18°C. Seeds were killed by freezing when stored in paper bags at - 18°C. Mango seeds exhibited recalcitrant storage behaviour. In cvs. 'Alphonso' and 'Dashehari', seed longevity was extended from 15 days to 365 days by imbibed storage at 15°C. Phalsa seeds remained viable for 5 years at 5°C and -18°C. Seeds of grape cv. 'Bangalore Blue' could be preserved for 2 years at 5°C and - 18°C. Dormancy could be eliminated by treating seeds with gibberellic acid (2000 ppm).

Vegetable seeds exhibit orthodox storage behaviour and are easy to conserve. Genetic differences for seed longevity were observed in onion, chilli, cauliflower and brinjal, and classified as short, moderate and long term for storage under ambient conditions. Seed maturity which affects the storage life varied from several days to weeks in different vegetable crops. Seeds from immature fruits did not germinate in chilli cvs. Pant C-1 and Arka Lohit. Seed longevity and vigour were higher in seeds harvested at ripe to overripe stages which coincided with the presence of high quantity of total proteins and free amino acids in seeds. Drying at higher temperature (40°C) damaged the seeds and resulted in low percentage of germination in okra. High percentage of germination was obtained in chilli when fruits were stored in cloth, paper and polyethylene bags. The incidence of insect attack was more in polyethylene bag-stored fruits.

Effect of antioxidants and inhibitors on storage life of seeds: Effect of chemical treatment with certain antioxidants and inhibitors has been studied in seeds of radish, onion, French bean and cowpea. In radish, 2, 4-dinitrophenol at 0.08% significantly reduced germination while other chemicals like EDTA, borax, potassium metabisulphate (KMS), oxalic acid, ascorbic acid, abscisic acid (ABA), maleic hydrazide (MH), glucose and polyethylene glycol (PEG) preserved the seed viability. Germination of French bean seeds was affected by all the chemicals except glucose. Abscic acid (ABA) and maleic hydrazide (MH) treatment in onion significantly reduced the germination. Similarly, seed germinability was affected by all the chemicals in cowpea.

Studies on seed storage under controlled temperatures showed that seed could be stored for 10 years in onion, radish, French bean and cluster bean, 8 years in bell pepper and watermelon, 7 years in okra and 4 years in brinjal, tomato, long melon, amaranthus, bottlegourd and pumpkin by storing seeds at 5°C and - 18°C. Polyethylene aluminium foil laminated bags and glass containers gave better results than paper containers, especially at sub-zero temperatures, for seed storage.

It was observed when seeds of bell pepper, chilli, lablab bean, okra, onion and watermelon were packed in aluminium foil laminated bags under partial vacuum and stored under ambient conditions, the percentage of germination and seedling vigour were greater. The percentage of germination was higher in nitrogen atmosphere than in carbon dioxide in muskmelon, okra and onion, while with bell pepper it was high with cabron dioxide. Seedling vigour was not affected.

Studies on physiological and biochemical changes in stored seeds indicated that the electrical conductivity, soluble sugars and free amino acid contents were greater in leachates of ambient stored seeds than the low temperature stored seeds. Similarly, dehydrogenase activity decreased in seeds stored under ambient conditions, accompanied by loss of seed germinability and seedling vigour.

Preliminary studies indicated possibilities of conserving orthodox seeds in suitable liquid embedding medium for long term at ambient temperature avoiding refrigeration. Pollen storage: Studies in papaya and citrus have shown that pollen could be kept viable for durations ranging from 2 to 6 months in domestic refrigerators at temperature ranging from 5°C to - 18°C. With the establishment of constant temperature regime, pollen under low temperature conditions could be kept viable beyond 6 to 8 months at - 18°C to - 20°C, but with a gradual decline in viability tested under in vitro conditions. Freeze dried pollen stored at - 20°C retained viability and fertility upto 14 months of storage in papaya. Uniform low temperature (either at + 5°C or at - 20°C) was found to be very critical for retaining good viability for short and medium term storage. The decline in viability is more rapid at 5°C than at - 20°C in pollen of different cultivators. Pollen samples have been stored at - 20°C in the genebank since 1992. Field pollination's using low temperature-stored pollen of papaya, citrus, grape, tomato, brinjal, rose and gladiolus resulted in satisfactory fruit and seed set with reduced frequency as compared to control. Seeds set through stored pollen germinated rather slowly as compared to seeds obtained through open pollination, indicating loss of seed vigour. Mortality rates were quite substantial at seedling storage, which impeded complete establishment of plants.

More than 400 pollen samples of 26 different species belonging to fruits, vegetables and ornamental crops have been successfully cryopreserved in liquid nitrogen for ten years in 5 cryogenic containers. It was observed that in almost all the crop species a good measure of viability and fertility could be retained by storage in liquid nitrogen. In fruits such as papaya and grape, pollen have been successfully cryopreserved for 7 years retaining good viability which induced fruit and seed set when used in hybridization programmes. Citrus and mango pollen have been kept viable under cryogenic conditions for durations ranging from 1 to 4 years and pollen fertility checks were successful after cryostorage.

Among vegetable crops, tomato and egg plant pollen have been cryopreserved for durations as long as 8 to 9 years, respectively. Cryopreserved pollen responded to fertility tests carried out through field pollination exceedingly well, producing seeds similar to those from fresh pollen. Onion pollen cryopreserved for 6 years emerged successfully when tested for fertility under field conditions. Capsicum pollen kept for a duration of 2.5 years in liquid nitrogen was viable in vitro and fertile. Rose pollen was cryopreserved successfully for one year. In all crops tested, no decline in viability was observed.

Development of viability assays for stored pollen: The pollen storage laboratory has optimised a number of procedures for testing pollen viability in vitro.

i) In vitro germination in liquid media-modified hanging crop technique, germination in liquid media-modified cellophane technique;

ii) In vitro germination of pollen tubes in stellar material;

iii) Influence of magnetic stimulus to accelerate germination rates in vitro;

iv) Instant pollen tube formation in an acidic media; and

v) Use of fluorescent dyes to index viability.

Results of the viability tests indicated that in general there is a very strong direct correlation between pollen germination and seed set, in some crops, and in some cases an inverse correlation was found between germination and seed set.

In crops like papaya, citrus (trifoliate orange), banana and tomato, breeders have utilized the pollen storage, protocols developed at IIHR in their breeding programmes.

Varieties released

Over the years, IIHR has released a number of varieties/hybrids in fruits, vegetables, ornamental, medicinal and aromatic crops.

Fruit crops


Four hybrids have been released in mango so far. They are 'Arka Aruna (Banganapalli × Alphonso), 'Arka Puneet' ((Alphonso × Banganapalli), 'Arka Anmol' (Alphonso × Janardan Pasand) and 'Arka Neelkiran' (Alphonso × Neelum). All the four hybrids are regular bearers and do not have spongy tissue problems. Arka Puneet has excellent colour with red blust and Arka Anmol has excellent keeping quality. Both these have export market. Arka Neelkiran is a late crop.


Four grape hybrids, viz., Arkavati, Arka Kanchan, Arka Shyam and Arka Hans have been released after a decade of work on breeding prior to 1985. During 1992, seven superior grape hybrids, four of them "or table purpose, one for juice and two for wine were identified for release. Among these, Arka Neelamani is a black seedless with crisp pulp.

Passion fruit

A promising hybrid between purple and yellow-fruited varieties has been evolved at Chettalli. The hybrid is high yielding and tolerant to leaf spot, root rot and resistant to root knot nematodes.


A variety by name Coorg Honey Dew was evolved at Chettalli Regional Station and an improved papaya selection Pink Flesh Sweet was released by IIHR, Hessaraghatta.


Two soft seeded guava varieties Arka Mridula and Arka Amulya have been released.


One interspecific hybrid in annona named as Arka Sahan has been released which has good keeping quality and high TSS.


One selection in litchi has been identified and released from CHES, Ranchi under the name Swarna Roopa which is resistant to fruit cracking with high TSS. This is the first litchi variety released in the country.


A promising ber selection CHES-1 from variety Umran has been released which is earlier than Umran, high yielder and escapes insect, pest disease problems and has been christened as Gomati Kirti.


Two pomegranate hybrid with dark red arils and soft seeded superior to Ganesh seedless have been developed and are in the advanced stages of testing.

Vegetable crops

The Institute has so far released 57 improved vegetable varieties of which 31 varieties have been released at the national level and 26 varieties have been released at the state level. Major breakthrough has been made by developing okra varieties Arka Anamika and Arka Abhay resistant to yellow vein mosaic virus, tomato F1 hybrids Arka Abhijit and Arka Shreshta resistant to bacterial wilt, onion variety, Arka Kalyan tolerant to purple blotch and muskmelon variety, Arka Rajhan resistant to powdery mildew. Breakthrough has also been made in evolving multiple disease resistant varieties like Arka Manik watermelon with triple disease resistance to anthracnose, powdery mildew and downy mildew.

Ornamental crops

The Institute has released 74 varieties in various ornamental crops, viz., gladiolus, bougainvillea, hibiscus, China aster, chrysanthemum, rose, tuberose, croton, etc. These have been bred for various traits like colour, loose flower, display and bedding purposes and resistance to pest and diseases. Protocols have been developed for in vitro propagation of orchids and anthuriums.

Medicinal and aromatic crops

In medicinal crops, first breakthrough was made in 1974 by developing two varieties in Dioscorea, viz., Arka Upkar and FBI(C)/1 having high diosgenin content. Similarly, Arka Sanjeevini a less spiny variety and Arka Mahima a tetraploid with high solasodine content in Solanum viarum have been developed and are being commercially grown for production of steroids for family planning purposes. In aromatic crops, one Jasmine Selection Arka Surabhi has been identified for release which has high oil content.

Crop Production

Fruit crops


In mango, contribution of tree age towards yield is important and fertilizer scheduling has been made age specific. Vellaikolumban rootstock imparted dwarfing in Alphonso scion and tree volume was reduced by 40 per cent with higher productivity. Shedding of fruits in mango beyond marble stage of growth was directly related to canopy size. Surface temperature was less in affected fruits as compared to fruits with spongy tissues. This could be made use to screen the fruits non-destructively. Paclobutrazol treated trees showed lesser total cytokinin activity and hence its possible dwarfing effect.


For Sardar guava, optimum fertilizer dose for higher yield was 900:600:600 g NPK/tree. But for increasing the fruit quality, the N should be reduced by 33%.


Papaya with 2262 plants/ha and six split applications of NPK (250:250:500g N, P2O5, K2O/plant/year) was the best for Coorg Honey Dew Cultivar.


High density planting in banana (4444 plants/ha) resulted in 33% higher yields. Drip irrigation in banana could economise the water by 25% and with a yield increase of 10%, fertilizer with nitrogen reduced the requirement by nearly 50%. Effective weed control could be achieved in banana using diuron at the rate of 2 kg a.i./ha.


Thompson Seedless and Arkavati grapes raised on 1613 rootstock gave highest yields. The best training system of yield and quality in Thompson Seedless grape was 8-arm Tatura and 12-arm Tatura for Arkavati grapes. Use of cycocel twice (1000 ppm) after back pruning and smearing with hydrogen cynamid (1.5%) after October pruning increased the cluster/cane ratio. Grape rootstocks (Dogridge and 1613) were found to exclude chloride in saline soils and water.

Citrus fruits

Rangpur lime and Cleopatra mandarin rootstocks could withstand higher levels of sodium and chloride in irrigation water.

Leaf sampling technique was standardized for grapes, mango, banana, citrus, guava, pineapple, pomegranate, sapota, custard apple, papaya, passion fruit, jujube and phalsa for identifying the nutritional disorders.

A computer programme has been developed for fertilizer recommendations of different fruit crops. Best time of application and methods of placement of fertilizer have been worked out of sweet orange, Coorg mandarin, banana, Thompson Seedless grape and mango (Alphonso) based on root activity studies. Efficient citrus rootstocks of N, P and Zn absorption have been identified. Zn deficiency in sweet orange, complex bronzing in guava and B deficiency under high density planting in banana have been identified. Remedial measures have been recommended to rectify the disorders using micronutrients.

Vegetable crops

Plant population density and optimum fertilizer requirements have been worked out in crops like tomato, egg plant, chilli, capsicum, cauliflower, cabbage, onion, okra, French bean and pumpkin.

Optimum agronomic practices like sequential-intercropping system, fertilizer and plant density levels for seed production, water requirement and optimum soil moisture regime for various crops have been worked out.

Moisture stress at flowering was found critical for crop growth and yield in French bean (Contender). The middle node pods in okra are strong sinks for photoassimilates and could be used effectively for seed production. Spraying parachlorophenoxy acetic acid improved the fruit set (70%) and more size in Arka Saurabh, a heat sensitive tomato variety. Bioassay technique for herbicide residue detection has been standardized.

Salt tolerant lines in various vegetables, such as tomato, brinjal, okra, chillies and onion have been identified for use in marginal saline soils and water where electrical conductivity of the growing medium is between 2.5 and 5.0 dSm-1.

Nutrient efficient (NPK) selections/ varieties in tomato, IIHR 550, IIHR 837, Arka Saurabh, Arka Vikas and Pusa Ruby can be directly utilized in the cropping programme as well as in marginal lands as they require less fertilizer and leave very Little residue in the soil eliminating the hazards of salinity and pollution besides reducing the cost of fertilizer input. They can also be utilized in the breeding programme.


A model mini bulk chamber was developed for composting and room pasteurization methods were standardized. Shtick mushroom was successfully cultured for the first time in this part. Sporeless and low spore shredding strains of Pleurotus sp. have been developed. Studies on competitor molds associated with mushrooms and its control measures were worked out. The mushrooms laboratory is for the development of the industry in south India and assists by providing training, guidance, technological information and spawn.

Ornamental crops

Pruning to 4-5 buds on the cane has yielded optimum flower production in rose. NPK 250:500:375 kg/ha was found to be optimum for flower production in rose planted closely. Planting gladiolus during the months of June and October-November yielded good quality spikes. Planting during the month of April-May was found to be the best in case of tuberose and planting of bulbs in flat bed was better than ridge planting. Protocorms of some orchids have been successfully encapsulated for storage and delivery and micro propagation techniques have been standardized. Micropropagation methods for anthuriums have been standardized for faster multiplication.

Medicinal and aromatic crops

Diosgenin assay procedure has been developed. Incubation techniques have resulted in obtaining higher diosgenin yield (16 to 58%) from Dioscorea floribunda tubers. Acid hydrolysis method of solasodine estimation has been developed. An increased yield of 8 to 12% essential oil from scented geranium was obtained by distilling the herbage after 17 hours but before 24 hours of harvest.

Crop Protection

Fruit crops

An Integrated Pest Management (IPM) strategy for control of fruit fly Bactrocera dorsalis on mango by a combination of cultural practices, spray at critical crop stages and post-harvest treatment of fruits in saline solution has been worked out. Biological control techniques were developed for the pink mealy bug, Maconellicoccus hirsutus on grapes with release of Australian lady bird beetle, Cryptolaemus montrouzieri and of citrus mealy bug (Planococcus citri) using the parasitoid, Leptomastix dactylopii. An integrated management of citrus nematode Tylenchulus semipenetrans in citrus has been developed. In grape, critical period of downy mildew disease has been identified to undertake effective and economical chemical control. Biochemical factor for disease resistance has been worked out. In mango, sunshine hours (5 hours or less) play a major role in increasing powdery mildew disease. Several chemicals were found effective in checking the disease. For papaya and ber, powdery mildew, sunshine and relative humidity at 14.30 h had a profound impact on disease development. Extensive survey on guava wilt has been conducted in different parts of the country and five Fusarium spp., Botryciplodia sp. and Pestalotiopsis sp. have been reported. Post-harvest studies have established the occurrence of Pseudomonas sp., Enterobacter sp. and Penicillium sp. antagonistic to fungi causing fruit rot of guava. Treatments were also standardized to combat post-harvest and storage loss in banana and mango. The causal agent of Blastomania of citrus was identified as mycoplasma like organism (MLO). A bacilliform virus was discovered in pumello plants. Papaya ringspot virus was the most devastating on papaya and a wide variation was noticed among several serological groups in India. Copper resistance was noticed in field isolates of citrus canker pathogens. Cultural and chemical control were also standardized. Causal agent of pomegranate nodal blight has been confirmed as X. campestris pv. punicae.


Integrated pest management (IPM) strategies for major pest complex on cabbage and cauliflower with Indian mustard as a trap crop and African marigold as a trap crop for fruit borer (Helicoverpa armigera) on tomato have been developed. Optimum number of sprays for the management of beanfly and pod borers in leguminous crops as well as for fruit borer in okra and brinjal have been worked out. A sporeless mutant of Bacillus thuringiensis was isolated and utilized for the management of diamondback moth on crucifers. Nuclear polyhedrosis virus was isolated and used for the management of fruit borer on tomato. Root knot nematode Meloidogyne incognita in tomato and brinjal has been controlled by using oil cakes, endomycorrhizae and bio-agents like Trichoderma harzianum, Verticillium chlamydosporium and Paecilomyces lilacinus. Thai Sac brood disease of honey bees, which had brought down the number of bee colonies from 60 000 to 4000 was effectively controlled by inoculating an anti-viral agent.

A root-dip technique has been developed against Fusarium wilt of chilli and inoculation technique against Alternaria fruit rot of chilli and capsicum. An inoculation technique for screening against onion basal rot and root rot of pea have been developed. Sphaerotheca fulginer was found to be the most predominant among powdery mildew pathogens of cucurbits and control measures through chemical and cultural practices have been standardized for major diseases. Soil borne pathogens can be checked significantly by solarization using polythene sheets to trap the heat change. Different MLO diseases of tomato and legumes have been identified. Sources of resistance to yellow vein mosaic of okra were identified. Molecular diagnostic technique for TLCV using DNA probe is developed for detecting TLCV in tomato and chilli. Fungicide combination of copper oxychloride and zinc based chemicals are effective for controlling the disease.

Memordicines from bitter gourd leaves showed antecedent activity against red pumpkin beetles and antifungal activity against Colletotrichum gloesporoides. The alkaloid serpentine present in roots of catharanthus showed in vitro nematicidal activity against root knot nematodes. Scented geranium oil and its constituent geraniol and citronella as well as methanol extract of onion seeds showed both antifungal activity against C. gloesporoides and nematicidal activity against root knot nematodes.

Ornamental crops

Disease control methods were worked out for all important diseases of rose, gladiolus, chrysanthemum, jasmine, marigold, zinnia and crossandra. Isolates of Fusarium oxysporum f. sp. gladioli obtained from commercial farms of gladiolus were found to be Race-1 of F. oxysporum. Phetalaxyl was found to be phototoxic to crossandra among anti-oomycetes. Disease resistant sources were identified in rose and gladiolus. Effects of different domestic processes were studied to recommend the decontamination of residues from fruits and vegetables as worked out for use under domestic conditions. In vegetables, placement of fertilizer 5 cm below the seed/plant row showed maximum utilization and as a result, 20% of saving in P input was achieved in tomato and onion and 40% in brinjal.

The persistence of various insecticides and fungicides on tropical fruits and vegetables was determined and safe waiting periods in terms of days required to be lapsed between the last application and harvest were determined, so these can be safely consumed without causing toxicity problems. The degradation of pesticide residues in soil following their build up during pest control operations was studied in different soils. Carrot and cauliflower responded to the application of B at the rate of 2 kg/ha as borax. Boron efficient lines in carrot and cauliflower have been identified.

Crop Utilization

Handling and storage

Optimum maturity standards for mango, banana and tomato have been determined. Use of gibberellic acid and Vitamin K3, skin coating with Gal-prolong and Semperfresh enhanced the shelf life of mango by 2 to 4 days at 25°C.

Individual shrink wrapping of capsicum, cucumber and pomegranate and storing at cool temperature (6°C) showed a significant extension of shelf life upto 30 days. Use of ethylene absorbent in banana extended the shelf life both at 15°C and 21°C by 6 and 3 weeks respectively. Cultivars of grapes can be stored for 2-3 months at 1-3°C using grape guard. Waxing of Coorg mandarins can extend shelf life when held at 25 and 10°C. Pre-harvest nutritional status was observed to influence the post-harvest decay in onion.


Methods have been standardized for preparation of dehydrated products by freeze drying and osmotic dehydration from mango and banana. Technologies for raisin making, watermelon juice and banana beverage have been developed.


Methods have been standardized for making different types of wines. A method has been developed to make acceptable quality wine from high acid Bangalore Blue grapes. Vinegar with fruit flavour has been prepared from processing wastes. Methods for preservation of cut vegetables by lactic fermentation have been standardized.

Other Aspects

Economics and statistics

The predominant role/expression of the female parent in crosses was established in 25 different crops. For the first time in the country, work on statistical ecology of insects was done and very useful information on the behaviour of the pest, its weakest point in life and sampling and forecasting methods were evolved. A novel method of finding out optimum plot size in plant protection trials was evolved for the first time. Generalised models for predicting fertilizer requirement of a crop based on available literature was built up in case of tomato. Using this fertilizer recommendations could be given village-wise. Expert system for guidance of cultivation of grapes and mushrooms was built up and supplied to the growers. Knowledge base of package of practices for 155 different horticultural crops was established for the four southern states. The cooperative marketing structure of horticultural crops was studied and many improvements for deriving better returns under efficient management were suggested. The working of cold storages were studied and economic inadequacies pointed out. The feasibility of cooperative small scale processing units in tomato and mango at village level was established.


During the last ten years, training programmes have been conducted at various levels to clientele such as state level officers of agricultural departments, university professionals and semi-government, voluntary organizations along with private enterpreneurs. In the last ten years, 2459 persons have been trained by this Institute on various aspects of horticultural production technologies through 128 training courses. Horticultural technologies released by the Institute were disseminated to officials of state departments, non-officials, farmers and entrepreneurs using variety of extension methods, which include in service training, organization of field days, arranging exhibitions, advisory services to farmers, radio talks, TV talks, organization of film and video shows, publication of extension bulletins and folders, field demonstration of new IIHR varieties.

Training of farmers

This is being done at the Krishi Vigyan Kendra at Gonoikoppal at Kodagu District.

Around 8000 farmers, farm women and youths are trained in horticulture and related inputs every year by the KVK.

Advisory services

The soil and water samples received from farmers of Karnataka, Maharashtra and Tamil Nadu are analysed on payment basis and the nutrient status and fertilizer recommendations are sent to them for adoption.

Agricultural Engineering

A continuous, motorised raw mango peeler of 200 kg h-1 capacity for pickle and chutney industries has been developed. By this, a saving of Rs.600/- can be effected when compared to manual peeling of one tonne. The time and manpower also is considerably saved. A fruit mechanised grader has also been developed for mango. Suitable packages for export of mangoes and pomegranate have also been developed.


In a recalcitrant crop like mango, culture of nucellus and hybrid embryos from direct crosses yielded plantlets. Salt tolerant grape rootstock has been micro-propagated for its use on large scale. Hybrid grape variety Arka Neelmani has been multiplied in large scale for distribution to farmers. An efficient Sachet technique has been standardized for rapid acclimatisation of micropropagated grape.

Vesicular arbuscular mycorrhizal fungi and phosphate solubilising bacteria when inoculated to crops like papaya, banana and mango were found to substitute 50% urea and super phosphate in papaya cv. Coorg Honey Dew. 50% urea increased yield by 15-20%. In mango, cv. Arka Aruna, inoculation of VAM fungi improved plant growth. Nitrogen fixing bacteria colonising endorhizosphere of tomato, capsicum and brinjal have been isolated and their contribution to nitrogen economy has been found to be 20%. Bacteria isolated from tomato endorhizosphere has been identified to be a new species of Azospirillum. For the first time in India, a TLCV-in specific nucleic acid probe has been developed for gemini virus.

Expert Systems/Computer Aided Information

Considering the fact that computers are available in almost every district headquarters and also the fact that these programmes in Indian context can be used by extension personnel for solving the problems of cultivation, the Institute has initiated steps to use computers for transfer of technology in horticulture by developing expert system in various horticultural crops which can provide all the information about production technologies including propagation, cultivation, plant protection, package of practices and product utilisation. Work in this direction has successfully resulted in developing Grape Expert System, Mushroom Expert System, Cabbage Pest Expert System, Personal Computer based pest information on tomato and serpentine leaf miner information oriented computer aided system (SLM - INFO).

Apart from these, a new computer information system giving recommended guidelines on all aspects of cultivation of 153 horticultural crops (including plantation crops, tuber crops and spices) which gives recommended package of practices for each crop in Karnataka, Andhra Pradesh, Tamil Nadu and Kerala has been released. A data base programme giving guidance as to the fertilizer and spacing requirements of horticultural crops in India, statewise has also been developed to facilitate the extension worker, the planner or the cultivator to get within a few seconds the appropriate recommended doses of fertilizers, in whichever state he resides which will be released to general public for use shortly.

IPGRI-APO Activities On Plant Genetic Resources: Present Status and Future Plans - V. Ramanatha Rao


Plant genetic resources (PGR) form a major component of the biological diversity. Effective conservation and sustainable use of PGR is a problem for the whole humankind, one of the many problems of our times (Ramanatha Rao and Tao 1993). There are several natural and human made reasons, such as environmental destruction, over-exploitation, replacement of traditional cultivars, modernization of agriculture for the rapid loss of genetic diversity available for human welfare. Many countries and organisations have been involved in the efforts to mitigate the situation over the last two decades. Due to largely unpredictable needs of the future, PGR have to be collected and conserved for future use before they disappear for ever.

Asia, the Pacific and Oceania (APO) region contains approximately 45 countries with little over half the world's population living in this region. Due to the diverse climatic and ecogeographical conditions, a great amount of genetic diversity can be found in this region. Agroecological features vary from highlands, semi arid tropics to humid coastal plains with climate varying from temperate to tropical. Additionally, the cultural diversity, these rich mosaic of peoples and cultures, each selecting and using genetic resources to suit their particular needs, is another factor of primary importance in the development of the enormous diversities found in cultivated plants in the region (Ramanatha Rao et al. 1996). The APO region is a major centre of plant domestication and diversity, and includes Indian, Indonesian, Indo-Chinese and Melanesian centres. Domestication of crops, such as eggplant, pigeonpea and cucumber, soybean, onion, cabbage, peach and foxtail millet, oriental rice, banana, citrus, yam and taro, mango, coconut, and breadfruit has occurred in this region (Frankel and Hawkes 1975; Harlan 1961, 1971, 1992; Purseglove 1976; Zohary 1970). In addition, the genetic diversity in both indigenous and introduced species is extremely large due to extensive exchange of material within the region and other regions (notably from Americas) (Ramanatha Rao et al. 1996). Recently, the International Technical Conference in June 1996 at Leipzig came up with the Global Plan of Action (GPA), focusing on agrobiodiversity (FAO 1996). CBD and GPA provide excellent guidelines for the effective conservation and use of biodiversity.

Many of the countries in the region are undergoing rapid changes in terms of trade, exports, urbanization, land-use pattern and market-driven and uniform farming practices. Despite positive aspect of such changes, they have contributed to significant loss of diversity in APO. The loss is in terms of both biological diversity and agrobiodiversity. Though, in recent years, the importance of both biodiversity and genetic diversify has been better recognised, increased support has been hard to come by. We need to remedy the situation.

The International Plant Genetic Resources Institute

The establishment of the International Board for Plant Genetic Resources (IBPGR) in 1974 helped focus attention on the need to collect and conserve the diversity of crops and related species. Little over the last two decades, admirable efforts have been made by different countries and the International Agricultural Research Centres (lARCs) to collect and conserve the diversity found in crop genepools. Collections now stand at well over 6 million accessions stored in over 100 genebanks around the world. Most of these accessions have been collected, conserved, documented and regenerated by countries for use both within and outside the country. By reaffirming that each country has a long term responsibility to conserve its own genetic resources, the Convention on Biological Diversity (CBD) has placed the responsibility to maintain and sustainably use the PGR on the countries themselves. The CBD has also reaffirmed the rights of the countries to benefit from their own PGR (Ramanatha Rao 1995).

IPGRI's Mandate, Objectives and Organization

IBPGR was established in 1974 to promote and coordinate the work on plant genetic resources globally and was linked to the Food and Agriculture Organisation of the United Nations (FAO) for administrative purposes. During the 20 years of its existence, along with many achievements to its credit, IBPGR has grown into a fully independent institute, the International Plant Genetic Resources Institute (IPGRI) which came into being in 1994. It is a member of the Consultative Group on International Agricultural Research (CGIAR) system. In addition to new elements on forestry genetic resources, IPGRI now has the International Network for the Improvement of Banana and Plantain (INIBAP) as a programme.

As indicated earlier, both agriculture and biological diversity are undergoing rapid changes caused by a number of interacting factors. In the future, it will be important not only to conserve these eroding PGR, but also to better understand the linkages between agricultural and economic systems that affect diversity and sustainable production. There is need to broaden our vision if more effective strategies for conservation and use are to be developed. The IPGRI strategy has been evolved taking into account all these factors. The mandate of IPGRI is to advance the conservation and use of PGR for the benefit of present and future generations and establish fundamental principles on which IPGRI will operate including:

· that people and their development are the foremost reasons for conservation of PGR,

· that genetic resources should be available, without restriction to all bonafide users, and

· that IPGRI should carry out its work through supporting and facilitating other organizations, rather than doing the work itself.

IPGRI has four programme objectives (IPGRI 1993):
1. to assist countries, particularly developing nations, to assess and meet their needs for conservation of plant genetic resources, and to strengthen links to users;

2. to strengthen and contribute to international collaboration in the conservation and use of plant genetic resources;

3. to develop and promote improved strategies and technologies for plant genetic resource conservation; and

4. to provide an international information services on plant genetic resources.

There are three programmes:
1. Plant Genetic Resources,
2. INIBAP, and
3. CGIAR GR Support.
There are two thematic groups located at IPGRI Headquarters in Rome:
1. Genetic Resources Science and Technology (GRST), and
2. Documentation, Information and Training (DIT).
IPGRI's regional activities are carried out under 5 regional groups:
1. Sub-Saharan Africa (SSA) in Nairobi,
2. West Asia and North Africa (CWANA) in Aleppo,
3. Asia, the Pacific and Oceania (APO) in Serdang,
4. The Americas (AM) in Cali, and
5. Europe (EUR) in Rome.
In the APO region, three offices carry out the regional activities. The main office is located in Serdang and the coordinating offices are located in Beijing (East Asia) and New Delhi (South Asia). The priority crops and areas of work were determined through extensive consultation in the region in 1991-92 and are periodically updated based on the various consultations that occur. The basis to achieve these objectives are a set of multidisciplinary projects, comprising a series of activities. These form a sort of network or matrix between the five regional offices and the headquarters in Rome.

IPGRI in Asia

Since its inception IBPGR, the forerunner of IPGRI, has been very active in Asia (Arora et al. 1991; Ramanatha Rao and Riley 1995; Ramanatha Rao et al. 1996; Riley 1996). To achieve the strategic objectives set for our work in the region, plans for various activities to achieve these objectives have been made. It is recognized that there are several areas in which IPGRI should be involved in the PGR work in the region. However, with the limited resources available to us, we need to be pragmatic and we need to prioritize our activities. All our activities are aimed to achieve our objectives which were explained earlier and are based on extensive consultation with our partners in the region. IPGRI's priority setting framework includes 3 elements: (1) the external setting, (2) the needs of the partners with whom we work, and (3) the internal setting including IPGRI's Strategy and Programme Structure and Medium Term Plan (Riley and Iwanaga 1996).

Strengthening National Programmes

IPGRI's support to countries in the region includes direct visits from staff to provide advice or consultation with the emphasis on enabling countries to assess and plan a national programme most appropriate for their own needs; support for national workshops on PGR; assistance in evaluating and collecting threatened germplasm; short courses and degree training in the region.

National Visits

Since the establishment of IPGRI-APO office in the region, IPGRI staff have visited most of the countries in the region at least once, and several repeat visits have been made to many countries. Such visits help IPGRI to understand needs and opportunities in these countries and provide advice, if requested.

National Workshops

IPGRI's assistance to national programmes in the region takes many forms. We provide advice on the development of appropriate national plans and strategies for the conservation and use of PGR and help to promote awareness on these policies and activities among the decision makers. Many countries in the region maintain genetic resource collections or genebanks. Often links with users of genetic resources, such as breeders, regional or international programme scientists or communities or NGOs are not strong resulting in poor utilization of the available resources. This situation needs to be improved by fostering links through national workshops which allows the identification of country priorities and is an important element of IPGRI's regional effort. In the last 4 years, four national PGR workshops (Lao PDR, Mongolia, Papua New Guinea and Vietnam (Nghia et al. 1995) were held. Two PGR policy workshops in Bangladesh and Nepal (Upadhyay et al. 1994) and three regional workshops in Bangladesh for South Asia (Arora and Ramanatha Rao 1996), Indonesia PGR Symposium for South-East Asia (Williams et al. 1996) and East Asia PGR Coordinators meeting in China (Ramanatha Rao et al. 1995) were also organized. During 1997, PGR workshops in Cambodia and Bangladesh were organized and a few other countries were visited to assess the PGR situation.

Although IPGRI no longer supports routine collecting of germplasm, assistance is occasionally provided to collect threatened diversity, for example, in Nepal and Mongolia. Assistance is also provided to countries to make proposal to donors to support PGR activities such as for Bhutan.


Strengthening human resources is an important aspect of strengthening national programmes. Generally speaking, we keep the national PGR coordinators informed about opportunities available in a wide range of PGR-related courses and graduate programmes, and assist in placing selected trainees into such courses. IPGRI also organizes annually short courses in the APO region, such as the current one. Training at technical and university levels is an important aspects of IPGRI's regional activities including assisting universities in the region in the development of curricula. Over the last few years, several regional training courses have been organized, which include training courses on information and documentation at MARDI, Serdang, Malaysia; conservation of vegetatively propagated crops at UPLB/ViSCA, Philippines; management of collections: INSA, Hanoi, Vietnam; Regional Seed Genebank Management training at NBPGR, New Delhi; Trainer's course on coconut, Manado, Indonesia; Taxonomy and genetics of rattans in Kuching and Luasong, Malaysia; the STANTECH Regional courses in Espiritu Santo, Vanuatu and Kandy, Sri Lanka. The current course on the conservation and use of tropical fruit species germplasm is another example. IPGRI is also supporting the University of Philippines at Los Banõs (UPLB) in initiating an M.Sc. Programme in PGR. This will provide graduate training opportunities in the region with support being channelled through a consortium of South-East Asian universities called SEARCA. Indian Agricultural Research Institute (IARI) and the National Bureau for Plant Genetic Resources (NBPGR), New Delhi as well as the University Putra Malaysia (UPM) and University Kebangsaan Malaysia (UKM) were assisted in developing post-graduate courses in PGR.

In-Country Linkages

In most countries, it has been found that the genebank-user linkages are poor. In many cases, valuable PGR are being lost from farmers (fields) due to the poor linkage between the two (Riley and Ramanatha Rao 1995). Instead of working separately, genebank managers and breeders must work together. This can be best achieved by evaluation, by both the genebank and breeding programme staff, to identify productive cultivars from local germplasm, to identify desirable genotypes from the accessions in the genebank. This could lead to joint monitoring of the benefits accrued from the use of PGR and help in making the value of conservation of PGR visible, which is essential to obtain sustained support from the policy makers. Better links will also result in paying increased attention to the question of genetic erosion due to the release of new and improved cultivars for general cultivation. They can collect local material well ahead of the release of the material which should be made a pre-requisite to release of new variety and associated production technology. The breeder and conservator can also identify locations where the new varieties may not be very useful and hence the local cultivars can continue to be in cultivation, thus ensuring on-farm conservation of landraces.

International Collaboration

Our second objective is to build international collaboration in the conservation and use of PGR (IPGRI 1993), by encouraging and supporting the formation of networks, both on crop and geographical basis. This has become more appropriate in the context of Global Plan of Action (GPA), which has been agreed by more than 150 nations at the International Technical Conference at Leipzig, Germany in June 1996, making regional and international collaboration as the corner stone for the PGR conservation and use (FAO 1996). The involvement of FAO, other UN organizations, International Centres (such as ICRISAT, CIP, IRRI and IPGRI) and regional programmes such as RECSEA-PGR will all be important in helping in exchange of germplasm, advice on information, technologies and public awareness that can improve the management of PGR in a country. The international linkages can assist national efforts in technology transfer, exchange of information, and scientific and technical cooperation (Ramanatha Rao and Riley 1994; Riley and Ramanatha Rao 1995). IPGRI is involved with a series of crop networks and regional networks in APO that enhance exchange of information, and germplasm and technologies among countries and institutions in these networks. Such networks can also help prioritize research and training activities that IPGRI and network members can undertake (Ramanatha Rao and Riley 1996; Riley 1996; Riley et al. 1995; Zongwen 1995).

Regional Networks

The IPGRI offices in Serdang, Beijing and New Delhi are presently acting as secretariats in facilitating 3 subregional networks - RECSEA-PGR (Regional Cooperation in South-East Asia on Plant Genetic Resources), EA-PGR (Regional Network for PGR Conservation and Use in East Asia), and SAC (South Asia Coordinators on Plant Genetic Resources). Formation of a Pacific subregional network is being considered. These regional networks help to focus on common needs and opportunities among countries in strengthening PGR activities in the region through collaboration. Such networks, which generally meet once in two years, also enhance personal linkages among PGR workers in the region, and assist in information and germplasm to be exchanged.

Crop Networks

Crop Networks focus on the conservation and use of a particular crop genepool or groups of plant species. Such networks vary greatly in size and style of operation, depending on priority and funding. IPGRI works closely with other partners who often take the lead in developing and sustaining these networks. A brief description of the types of crop networks that IPGRI supports in the region is described below.

The Coconut Genetic Resources Network (COGENT)

Thirty five countries around the world are active members of COGENT, which aims to increase benefits to coconut producers through improved conservation and use of coconut germplasm. This network has a coordinator based in the IPGRI-APO office, and is managed through a Steering Committee. COGENT has been able to attract considerable donor support and is active in collecting and evaluating germplasm, promoting multiple uses of coconut, and setting up regional coconut genebanks, and a common database of coconut collections around the world (Batugal 1996; Batugal et al. 1995; Ramanatha Rao et al. 1996; Santos et al. 1996).

The International Network for Bamboo and Rattan (INBAR)

This network was set up by the International Development Research Centre (IDRC) and is presently an international institute with active office in New Delhi, India. INBAR aims to improve the benefits to local communities through sustained conservation, improved production, harvesting, processing and marketing of bamboo and rattan species. IPGRI is responsible for the Biodiversity and Genetic Resources Working Group of INBAR which is undertaking a series of studies to locate and characterize the important diversity of these species in Asia. Such work will lead to effective conservation of the priority species through integration with the activities carried out in the entire network. The support from IPGRI, which includes a consultant's time is made possible through funding from Japan (Rao 1995, 1995, 1996).

Tropical Fruit Species

The great diversity of fruit species in Asia, their potential for providing benefits to local communities, and threat of genetic erosion of many of these species are reasons for identifying the conservation and use of tropical fruits in Asia as a priority activity. A series of studies have been undertaken to assess the status of the genetic resources of priority species in Asia, and undertake training, conservation and evaluation in specific locations. Efforts are underway to link these activities into Networking with partners in the region, principally through the Underutilized Tropical Fruit in Asia Network (UTFANET) which is supported by the International Centre for Underutilized Crops (ICUC), FAO and other organizations. Priority species include rambutan, durian, citrus species, mango, jackfruit as well as other minor species native to Asia (Arora 1995a, 1995b; Arora and Ramanatha Rao 1995).

Underutilized Crops

Buckwheat, lathyrus, safflower, sesame and taro have been identified as priority underused crop species for our focus in the region. These crops are locally important and are generally grown in marginal areas where both ecosystem diversity and genetic diversity are high. IPGRI collaborates with partners in the region in carrying out specific studies on conservation related aspects and promotes networking and collaboration on these crops. For example, a sesame meeting was organised in India in 1994 which resulted in informal networking that included evaluating and exchange of germplasm among 12 Asian countries; the development of sesame core collection, and sesame germplasm adaptation studies. The world's sesame collection held in Korea has now been regenerated. A consultancy with the Australian Centre of International Agricultural Research (ACIAR) and the South Pacific Commission (SPC) is presently underway to assess needs for taro genetic resources conservation, improvement and sustainable production and develop a proposal for a taro network in the pacific. A lathyrus germplasm directory, in situ conservation studies in buckwheat, and compilation of the medicinal uses of safflower are examples of collaborative activities being carried out on the other underutilized crops. In each case, a network working group meeting has brought together the key researchers on these crops who continue to share information and germplasm (Arora and Riley 1994; Dajue et al. 1993; Ramanatha Rao 1994; Ramanatha Rao and Ming-De 1993; Ramanatha Rao and Riley 1995; Zhou and Arora 1995, 1996).

Networks with other International Agricultural Research Centres

IPGRI joins hands with other lARCs which take the lead in developing networking with NARs for the conservation and use of mandate crops. For example, in 1995, IPGRI collaborated with the International Potato Centre (CIP) in developing a concept paper and in holding a workshop with national programme scientists that addressed a strategy for conserving sweet potato biodiversity in Asia in May 1996 (Ramanatha Rao 1996, Ramanatha Rao and Schmiediche 1996; Riley 1996). A network called the Asia Network for Sweet Potato Genetic Resources (ANSWER) was formed. A series of activities including training, joint database of collections, rationalization of collections and complementary conservation methods are now being developed.

In the case of rice, IPGRI participates in the Steering Committee project concerned with conserving the rice genepool through further collecting programmes; and in situ conservation studies in the rice being carried out by the International Rice Research Institute (IRRI) and national programmes.

While IPGRI sees networks as tools that can promote more effective collaboration, supports strengthening national programmes and exchange information, and develops improved technologies for conservation and use, our resources are limited, and some integration of these networks may be desirable (Ramanatha Rao 1996; Ramanatha Rao and Schmiediche 1996; Riley 1996).

Conservation Strategies and Technologies

IPGRI's third objective is to develop and promote improved strategies and technologies for PGR conservation. Since no crop genepool can be effectively conserved using any one method, development of complementary conservation strategies is linked to this objective. A number of technologies and research approaches are now under development, which can offer national programmes improved methods of PGR conservation and use. Various methods of conservation, along with seed and in situ conservation, can be combined into a complementary conservation strategy for any given genepool. Advances in in vitro conservation technologies have made such methods practical for a wide variety of species (Ramanatha Rao et al. 1996; Ramanatha Rao and Riley 1994; Withers 1993). Further research on practical methods of low moisture seed technologies is still required before this technology can be used for maintaining seed with less or no refrigeration. Cryopreservation methods are under development, and may soon be more widely used for long term storage of base collections (Bajaj 1995; Engelmann and Ramanatha Rao 1996; Sakai 1995).

Rapid advances in molecular and isozyme markers enable studies on genetic diversity of collections to be carried out much more precisely. Possibilities for such technologies include improved monitoring of genetic diversity in genebanks and for measuring and locating genetic diversity in the field to assist in collecting and in situ conservation. The improved understanding of extant genetic diversity can assist in the enhancement of its use for accelerated development of desirable cultivars that are urgently required to meet the increasing demands of ever increasing population (Ramanatha Rao and Riley 1994).

In situ conservation approach to conservation, though the most desirable one, has only recently received increased attention (Hodgkin et al. 1993; IPGRI 1994). It is well recognized that farmers have been conserving high levels of diversity as part of traditional management practices. More studies are planned to establish the scientific basis for in situ conservation and to understand how in situ conservation can be included as an important component in a complementary conservation strategy. Although we earlier noted that spread of HYV may result in rapid genetic erosion, for a number of reasons it may not always be so. Linear replacement of traditional technology has been questioned (Just and Zilberman 1983). It has been shown that farmers, especially the subsistence farmers in marginal areas tend to maintain and manage fairly high levels of genetic diversity on farm and in farming communities (Altieri and Montecinos 1993; Brush et al. 1994; Brush 1992; Brush et al. 1992). Increased emphasis on the socio-economic and cultural aspects of conservation and use of PGR at the community level to insure that conservation of PGR is part of the development process, and that the role of farmers and local communities in maintaining and sharing PGR is recognised and enhanced, particularly in less favoured or marginal agricultural areas where diversity is high.

In the crop and commodity areas, IPGRI-APO emphasis is on coconut, tropical fruits, underutilized crops, and bamboo and rattan. In case of tropical fruits, focus is on priority genepools of both major (mango, citrus, rambutan) and minor (durian, litchi and jackfruit), and fruits of local importance. In case of taro, IPGRI had participated in PNG-Indonesia taro meetings in the past. Efforts are now underway to develop a taro genetic resource network in the Pacific. Within the underutilized crops, we have a task on potential crops in which yams and sago are included. Currently the interest is on gathering information on the status of these crops. We plan to work more on specific activities related to genetic diversity and conservation issues, once sufficient information is gathered and funds become available.

Forestry genetic resource (FGR) is another major area that requires urgent attention. IPGRI now has a major project on PGR including the work on bamboo and rattan (Ramanatha Rao and Rao 1995; Rao et al. 1997; Rao and Ramanatha Rao 1995a, b; Rao and Ramanatha Rao 1996a, b). It mainly aims at improving the scientific basis for in situ conservation, improving methods for ex situ conservation and building an international information system on forestry species/PGR (Ouedraogo et al. 1994). A major area of focus will be research and technology development for seed conservation as storage is the major problem because most tropical forest species produce recalcitrant seeds. Locating diversity and studying the impact of extraction will be other areas on which we will focus in the near future.

International Information Service

Our fourth objective is to provide an information service to inform world's PGR community of both practical and scientific developments in this field. Technical and scientific publications will be the major media through which the results of studies and new technologies will be conveyed to national programmes. The types of information that we provide includes descriptor lists to assist genebank curators and other PGR users, information that can be used to collect, manage and use germplasm, directories for different crops/commodities providing information on where particular germplasm is conserved and available for exchange, etc. The List of IPGRI publications (1995) contains all the titles published so far. Additionally, an effective public awareness programme will be put in place to increase the awareness on PGR issues among the general public as well as policy makers (public and corporate levels) so that PGR conservation will receive appropriate support at all levels.

Within this area, I would like to highlight our work on PGR documentation and information management as many tend to give less importance to it. Our aim is to develop the national capacity, to develop and sustain an effective national PGR information network. Of particular importance is the support provided to our partners to document and make better use of their own accessions in genebanks. A Data Interchange Protocol (DIP) has been developed to enable one genebank to receive and read information from another genebank using a compatible format. The DIP is now being used to exchange data on banana accessions in the region, and its application will be extended for use in Geographic Information Systems (GIS). A software known as Genebank Management System (GMS) development by IPGRI is used to train genebank curators in genebank documentation and management. GMS training has been carried out in Bangladesh, Indonesia, Malaysia and Vietnam. GMS is also serving as the genebank management software in several countries in the region including Malaysia. Plans include training in Nepal and Mongolia in 1997, and our work on information management also supports development of tools for information exchange such as the data interchange protocol (DIP) which has been tested (Yongsheng et al. 1995). It is well recognised that a well organised and maintained information system is an essential part of an effective conservation programme. IPGRI will support national programmes to develop such national PGR information systems (Quek and Ramanatha Rao 1995; Quek and Zongwen 1995).

In all the areas of technology development described earlier, rapid progress is being made. It is important that national PGR programmes should keep in touch with what is going on around the world. International collaboration is one of the ways to keep the flow of up-to-date information on new developments and their adaptation and adoption at national level. IPGRI also assists providing such information to its partners through newsletters and publications. Additionally, it organizes or supports several conferences or meetings to facilitate interaction of PGR researchers. Some examples in the recent years are workshop in users' perspectives to promote multipurpose uses and competitiveness of coconuts in May 1996; Regional coconut genebank planning workshop in February 1996; Regional workshop in Lathyrus genetic resources in Asia in December 1995, third South-East Asian symposium on genetic resources in August 1995, international workshop in in vitro conservation of PGR in July 1995; international symposium on research on conservation and use of PGR in June 1995, SPC/DAL/ IPGRI/FAO taro seminar in June 1995, and support for meeting in 1997 on seed technology, on citrus germplasm conservation focusing on rootstocks and biotechnology, at Brisbane, Australia.

Concluding Remarks

Thus, as indicated earlier, IPGRI considers the national programmes as the basis for a global system of PGR. Strengthening national programmes in terms of organization, technology, human resources and information forms, the basis of IPGRI's work on PGR. National programmes can best use such assistance when there is a clear recognition of the importance of PGR in a country and identification of organizations/individuals responsible for taking the work forward. From the initiation of the APO programme in the region, IPGRI has been supporting the organization meetings such as the present one to help the PGR workers in country to come together and discuss freely and chart out a programme of action for the country. Such a programme should consider all the issues discussed together and identify appropriate level of activity for the country as it may not be possible and even necessary for each and every country to have a large PGR programme. IPGRI is willing to support to the extent it can, mainly in the areas of techniques and advice, to assist national PGR programmes.


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Genetic Resources of Native Tropical Fruits in Asia: Diversity, Distribution and IPGRI's Emphasis on their Conservation and Use - R.K. Arora


The Asian region holds rich diversity in native tropical fruits which play an important role in providing food for local consumption. In South, South-East and East Asia, the local/ethnic communities have been growing diverse kinds of multipurpose fruits since distant past to provide sustenance to their livelihood. Native communities have contributed towards protection, domestication and selection of a wide variety of fruits in their home gardens and marginal lands, and are the custodian of such indigenous diversity occurring in diverse agro-ecoclimates of Asia. These communities also hold enormous local knowledge on conservation and use of native diversity. Realizing the importance of tropical fruits in Asia and that these have received relatively less attention in research and development, IPGRI in its regional programme, has laid emphasis to promote their conservation and use. Under the IPGRI project on 'Promoting Conservation and Use of Tropical Fruit Species in Asia' initiated in 1993, much progress has been achieved particularly in information gathering on distribution, diversity and status of genetic resources held by different key countries/national programmes. This lecture besides dealing with the distribution and extent of diversity occurring in major and minor tropical fruits in Asia, also focuses on the role of IPGRI in promoting conservation and use of such resources.

Species Diversity in Major and Minor Tropical Fruits

About 500 species of tropical fruits occur in this region (Singh 1993). The synthesized information on tropical fruits and nuts for South-East Asia enumerates 120 major and 275 minor species (Verheij and Coronel 1992). More important fruit crop diversity belongs to about 30 families and 59 genera. Overall, this diversity of cultivated and wild types is better represented in South-East Asia and South Asia than in East Asia. The number of wild species, their distribution, diversity and extent varies in different regions depending on their ecology, and most of these occur in seasonal or evergreen forests; the cultivated diversity being mainly distributed in the humid tropical/subtropical climates. About 90% of these fruits constitute the perennial vegetation composed of trees, shrubs and woody climbers. Taxonomic/floristic representation of important fruit species - families and genera is listed in Table 1.

Important native fruit diversity in this region is represented by fruits, such as citrus, banana, mango, rambutan, durian, litchi, jackfruit, mangosteen, longan, chempedak, langsat, salak, jujube and carambola/star fruit. Minor fruits of local importance are:

i) South Asia: Bael (Aegle marmelos), wood apple (Feronia limonia), amla/aonla (Emblica officinalis), jamun (Syzygium spp.), jujube, jackfruit, phalsa (Grewia subinequalis), khirni (Mimusops hexandra), mulberry, and tamarind (Tamarindus indica).

ii) South-East Asia: Durian, mangosteen, salak/salacca, langsat/duku, jackfruit and other Artocarpus spp., such as chempedak and marang, galo (Anacolosa), melingo (Gnetum gnemon), carambola, rambai (Baccaurea spp.) and pilinut (Canarium ovatum).

iii) East Asia/China in particular: Longan (Dimocarpus longari), kumquat, Clausena lansium, Chinese jujube.

Table 1. Important families and genera of tropical fruits in Asia




Mangifera, Bouea, Dracontomelon, Spondias, Buchanania






















Antidesma, Baccaurea, Emblica/Phyllanthus


Douyalis, Flacourtia






Parkia, Tamarindus, Dialium


Aglaia, Sandoricum, Lansium


Artocarpus, Ficus, Morus




Musa, Ensete




Eugenia, Syzygium






Salacca, Caryota, Phoenix, Arenga, Calamus






Citrus, Fortunella, Aegle, Clausena, Feronia, Poncirus, Limonia


Nephelium, Dimocarpus, Litchi


Bassia / Madhuca, Palaquium, Manilkara







Besides these, breadfruit is also important and is distributed sporadically in South-East Asia and in coastal regions of South Asia with more diversity in the Pacific islands. Table 2 lists some of these important indigenous fruits with their botanical and local names (Arora and Rao 1995).

Table 2. Some important indigenous tropical fruit species of Asia

Aonla, amla

Emblica officinalis Gaertn. syn. Phyllanthus emblica L.


Aegle marmelos (L.) Corr.

Banana and Plantain

Musa cultivated types

Ber, Jujube

Ziziphus mauritiana Lamk.


Artocarpus altilis (Park.) Fosb.

Carambola, star fruit

Averrhoa carambola L.

Chempedak, Champedak

Artocarpus integer (Thunb.) Merr.


Buchanania lanzan Spring


Lime, lemon, sweet orange, orange, mandarin, pummelo, grape fruit etc.

Date palm

Phoenix sylvestris (L.) Roxb., P. dactylifera L.


Lansium domesticum (Jack.) Correa.


Durio zibethinus Murr.


Anacolosa frutescens Bl.


Citrus paradisi Macf.


Spondias pinnata (Linn.f.) Kurz

Indian almond

Terminalia catappa L.


Artocarpus heterophyllus Lamk.


Syzygium cuminii (L.) Skeels


Ziziphus mauritiana Lamk; Z. jujuba Mill.


Artocarpus camansi Blanco


Carissa congesta Wt.


Mimusops hexandra Roxb. syn. Manilkara hexandra (Roxb.) Dub


Garcinia indica (Dupetit-Thouars) Choisy


Fortunella margarita (Lour.) Swingle


Lansium domesticum (Jack.) Correa


Citrus Union (L.) Burm. f.


Citrus aurantifolia (Christm. & Panzer) Swingle


Litchi chinensis Sonn


Dimocarpus longan Lour.

Malay apple

Syzygium malaccense (L.) Merr. & Perry


Mangifera indica L.


Garcinia mangostana L.


Mirnusops elengi L.


Citrus reticulata Blanco


Artocarpus odoratissimus Blanco


Gnetum gnemon L.

Monkey Jackfruit

Artocarpus rigidus Bl.


Morus alba L.


Citrus reticulata Blanco


Artocarpus sericicarpus Jarrett


Grewia subinaequalis DC. syn. G. asiatica Masters


Canarium ovatum Engl.


Nephelium ramboutan-ake (Labill.) Leech

Pummelo, pomelo

Citrus maxima (L.) Osbeck. Syn. C. grandis (Burm.) Merr.


Baccaurea spp.


Nephelium lappaceum L.

Rose apple

Syzygium jambos (L.) Alston


Salacca edulis Reinq = S. zallaca (Gaertn.) Vass

Sweet orange

Citrus sinensis (L.) Osbeck


Tamarindus indica L.

Water apple

Syzygium spp.

Wax jambo/jamby

Syzygium samarangense (Bl.) Merr. & Perry

Wood apple

Feronia limonia (L.) Swingle

Source: Arora and Rao 1995
Distribution and extent of diversity

Taking into account the major and minor fruit species diversity as discussed above, it is important to analyse the distribution and extent of variation occurring within these genepools. This information is mainly synthesized from Verheij and Coronel (1992), Arora and Rao (1995) and the status reports of IPGRI-APO (1996, 1997) on tropical fruits.

Mango and other Mangifera species

Kostermans and Bompard (1993) deal with 69 Mangifera species of which 12 have a doubtful status, thus about 57 valid species occur in this genus. Maximum species diversity occurs in South-East Asia, particularly in peninsular Malaysia, Sumatra and Borneo, and is well adapted to both monsoon and wet evergreen forests. Among these, 26-30 species bear edible fruits. Section/subgenus Mangifera (stamens with free filaments) has species, such as M. indica, M. altissima, M. griffithii, M. laurina, M. minor, M. monandra, M. pentandra, M. quadrifida and M. similis with maximum diversity in cultivated genepool occurring in India and in other parts of South Asia i.e. Bangladesh, Sri Lanka, Pakistan, Nepal; and in South-East Asia in Myanmar, Indo-China, Thailand, Indonesia and the Philippines, less so in Malaysia. In East Asia, limited diversity occurs in Southern China and in Taiwan. Section/subgenus Limus (stamens often with joint/connate filaments) includes species, such as M. caesia, M. foetida, M. kemanga, M. odorata, and M. pajang. These wild species and less known cultigens are distributed in Malaysia, Kalimanthan, Sumatra and Borneo. Natural hybrids occur in East Kalimanthan.

The cultivated diversity is more where monoembryonic forms are grown as in India/South Asia, as seedling populations present enormous variability. About 1000 types occur in India (Chadha 1995). Most varieties originated as chance seedlings. Commercially grown varieties number around 30. Some famous monoembryonic varieties are Alphanso, Dushahari, Langra and Totapuri. Polyembryonic varieties occur in coastal regions of India. Overall, maximum diversity of Indian origin occurs in monoembryonic varieties well distributed in South Asia, lesser so in South-East and East Asia. Polyembryonic forms occur as in the Philippines and diversity is limited in monoembryonic kinds. Hybrids of M. indica and M. foetida occur in Borneo and Java; within species variation occurs more in M. foetida and M. caesia. Among the wild species, M. kawini - a variety of M. foetida (its fruits possess good flavour and firmness) and M. gedebe are adapted to wet areas/water logged conditions.


Diversity is well represented in East Asia and South Asia than in South-East Asia. More wild species occur in Southern China, in the Indo-Burmese and Indo-China region. Citrus genepool of both cultivated and wild species falls within 16 species (Swingle's classification). Due to interspecific hybridization, much diversity occurs in citrus genepool. Taxonomically, this diversity belongs to two sections - Papeda and Citrus, and different types are recognized. Of the nine cultivated species in Citrus aurantifolia (lime, sour lime), more diversity occurs in Indo-Burmese region. In C. maxima (pummelo) in South Asia, more diversity occurs in Nepal and northwards to southern China and in the east in Japan and in South-East Asia, in Thailand, Malaysia and Indonesia. It is a monoembryonic species, consequently a wide array of variation exists. From Yunnan, new varieties (var. yunnannensis and muliensis) have been reported (Singh 1993). In cultivated forms, maximum diversity occurs in Thailand. In grapefruit (C. paradisi), thought to be either an interspecific hybrid of pummelo - C. maxima x sweet orange or a hybrid/mutant pummelo; white and pink fleshed forms exist. More diversity occurs in the Philippines and relatively less in Indonesia and in China. Citrus medica (citron) is distributed in the sub-Himalayan region, and is of Indo-Burmese origin. Its diversity mainly occurs in Indo-China and further in East Asia in China and Japan. In C. reticulata (mandarin) enormous diversity is reported from different geographical regions such as the Indo-China/ Indo-Burmese region, in southern China where ponkan types occur and in Japan particularly for satsuma types (C. unshiu), and in the Philippines. Also calamodin is of Chinese origin, a natural hybrid between a sour loose-skinned mandarin C. reticulata var. austra and a kumquat, Fortunella margarita. Citrus sinensis is considered to be of Chinese/ Indochinese origin, and more diversity occurs in this in southern China (C. junos and local types called zuzu/yuzu occur) and in Japan. Citrus is also cross and graft compatible with species from other genera of the Rutaceae; trifoliate orange, Poncirus trifoliata has been widely used as rootstock (Chadha 1995; Coronel 1995).

Wild species diversity is widely distributed in the Indo-Burmese region, such as of Citrus ichangensis, C. latipes, C. macroptera, C. assamensis and Citrus indica (wild mandarin), being more common in northeastern India and adjoining Myanmar. Diversity also occurs in this region in wild sweet orange, locally called Soh-nangriang in northeastern region, and in wild forms of C. limon (lemon). Citrus jambhiri (rough lemon), C. madaraspatana, C. pennivesiculata are widely distributed, particularly more variation occurs in the former.

Rambutan and other Nephelium species

Twentytwo species are distributed mainly in South-East Asia, of which 13 occur in Malaysia and 16 in Borneo, and 5 or 6 in Myanmar, Indo-China, Vietnam and Thailand, and one/two in South Asia. Of this diversity, 6 species produce edible fruits. Much variation occurs in N. lappaceum. Being a cross-pollinating species, it presents lot of variability in seedling progenies. It is the widely grown species. More diversity in East Asia occurs in southern China, and in South-East Asia in Indo-China, Thailand, Malaysia, Indonesia and the Philippines. Based on leaf characters, three varieties have been identified: var. lappaceum, pallens and xanthioides with obovate to ovate leaves and intermediate forms; the first widely distributed, the second more in East Asia and Indo-China, Thailand, Cambodia, Laos, Vietnam, Philippines, and the last more confined to Borneo. Nephelium ramboutan-ake (pulasan) is next to N. lappaceum in importance. Both these species possess juicy, aromatic, sweet aril; rind-colour varies from green, yellow to purple-black; in pulasan local variability occurs in Sabah with fruit of better quality possessing thick sweet aril of good flavour (Wong 1995).

Taxonomically, distinct varieties have been identified in N. cuspidatum known as the giant rambutan, var. robustum possessing larger leaflets and fruits (with dull red rind closely set with soft spinterns), aril/sarcotesta white and juicy with sour and sweet forms, the latter occurring more in Sabah. Other species represented are N. hypoleucum, N. glabrum, N. macrophyllum, N. maingayi and N. melanomiscum. Overall, within the major edible species, semi-wild and domesticated diversity exhibits variation in aril thickness, sourness/sweetness, juiciness and flavour. In wild/semi-wild and primitive forms, invariably the aril/sarcotesta is adherent to the seed. Among these, pulasan has sweeter and larger fruits with thicker and better quality aril.

Jackfruit and other Artocarpus species

About 50 species of. Artocarpus occur in this region, of which 11 are more important. Artocarpus heterophyllus (Jackfruit) originated in the Western Ghats of India, and has more diversity in India, Sri Lanka and Bangladesh in South Asia, relatively less in southeast and least in East Asia. However, more species diversity in genus Artocarpus occurs in South-East Asia in Indo-China, Thailand, Malaysia, Indonesia and the Philippines. Maximum diversity in A. integer (chempedak) occurs in Malaysia, while A. elasticus (A. semicicarpus) and A. nitidus (several subspecies occur) are widely distributed. Two other important species are A. odoratissimus (marang) which occurs wild in Borneo, but maximum diversity in cultivated forms occurs in the Philippines. Its fruit is small, but more sweet and juicy and considered superior to Jackfruit; and A. rigidus which is very productive, with smallest fruit in the genus, sub-sweetish but with vary good flavour, better than jackfruit, chempedak and marang. Several less known edible species such as A. sarawakensis are more localized or endemic in distribution. Natural hybridization in wild population of chempedak and jackfruit has resulted in more diversity in Malaysia. The cultivated types exhibit much variation in pulp quality, juiciness and odour. Several types possess better flavour to jackfruit. As compared to jack-fruit, diversity in breadfruit is less in South and South-East Asia, having much better representation in the Pacific.

Durian and other species

Twentyeight species occur in the genus Durio, mainly distributed in South-East Asia; 17 in Borneo, 23 in Malaysia. D. wyatt-smithii is related to durian. About 6-7 species bear edible fruits and occur in semi-domesticated/domesticated condition. The centre of diversity lies in Malaysia. Diversity in cultivated forms is distributed in Malaysia, Thailand, and Indonesia, less so in the Philippines and in the west in Indo-China and Myanmar, and further to China. Besides, D. zibethinus, D. dulcis, D. kutejensis and D. testudinarium are mainly confined to Sabah and Sarawak while D. grandiflorus, D. graveolens, D. oxleyanus, and D. lowianus are mainly distributed in Borneo. D. graveolens lacks aroma and possesses sweet aril and is early fruiting, D. testudinarium and D. lowianus are resistant to phytophthora. There is a wide variation in species, cross-pollination being common.

Litchi chinensis (lychee)

Litchi/Lychee originated in southern China. Three subspecies/varieties have been recognized: var. chinensis, var. philippinensis and var. javensis. Diversity in wild, semi-wild and or cultivated types occurs in southern China in Yunnan and Hainan provinces. For cultivated types, relatively more diversity occurs in Taiwan, Thailand and India, less so in Myanmar, Indo-China, Cambodia, Vietnam, Laos; eastwards to Philippines and Japan, exhibiting variation in fruit size, seed size, aril thickness, sweetness, juiciness, and to a limited extent in shape and surface. Genetic diversity is rather narrow. In southern China, 20-25 main cultivated types are recognized possessing characteristics, such as large fruit, small stone, thick free aril of good quality, sweet and juicy, with good flavour, and canning quality (Xuequin 1995).

Mangosteen and other Garcinia species

Garcinia is a large genus comprising more than 100 species, of which 30 species provide edible fruits, of which 8-10 are more important but all except mangosteen possess sour fruits. Garcinia mangostana (mangosteen), the better known cultivated species, is distributed in Malaysia, Indonesia, Philippines and Indo-China, Thailand, Vietnam and Myanmar. However, it exhibits narrow range of variability. Its nearest wild relatives are G. hombroniana and G. malaccensis distributed in Malaysia. In mangosteen very little variability exists, small leaved/small fruited and large leaved/large fruited types occur, much esteemed for their flavour and taste.

Longan/Dimocarpus: Dimocarpus longan (longan) is an underutilized fruit with more diversity in East Asia in southern China and Taiwan, in South-East Asia in northern Thailand extending to Indo-China where small fruited types occur in southern Vietnam; also sporadic distribution is reported in Malaysia and Borneo. East Asian diversity is of large fruits with sweet, juicy aril. Longan exhibits much infraspecific diversity/several botanical varieties have been identified based on leaf shape and fruit surface charactersitics (varieties obtusus, longi-petiolatus, echinatus). More variability is reported in var. malesianus in which about 30-40 local forms are known (Leenhouts 1971), some possessing sweeter, thickened aril as good as the longan (Wong et al. 1991).

Diversity is more represented in Sabah and Sarawak. Green and brown fruit forms, varying in fruit shape and size, and aril quality occur.

Langsat and related species

The genus Lansium comprises 7-10 species. Lansium domesticum (langsat, duku) originated in western South-East Asia from peninsular Thailand to Borneo in the east, where it is one of the major fruits. It also occurs in Indo-China, Vietnam and Myanmar. Langsat is a slender tree with acidic fruits while duku is more spreading type with sweet fruits. Intermediate types known as duku-langsat occur. Thus, considerable variation within the species occurs. Local type 'Kokosan' in Indonesia possesses sweet fruits with large seeds while longkong of southern Thailand has nearly seedless fruit with a brittle skin and soft aril. Overall, genetic diversity has so many intermediate forms that a taxonomically distinct grouping may be difficult.

Carambola/star fruit

The genus Averrhoa has two species, A. carambola and A. bilimbi, which are distributed in South-East Asia and Indo-Burmese region, and of these the former is more important. It is a variable species and many cultivars exist, maximum diversity being represented in Malaysia, and to lesser extent in South China and Taiwan exhibiting variation in fruit size, colour (green, yellow), shape, degree of sourness, juiciness and flavour.

Other species

Several other less known species of tropical fruits/nuts also occur in South, South-East and East Asia. Galo nut (Anacolosa frutescens) is distributed in Indo-China, Myanmar, Thailand, Malaysia, Indonesia and the Philippines. It is still an underdomesticated species. Variation exists in seedling populations in the Philippines where it is more important (Coronel 1995). Variability exists in fruit characters. Also, equally important in the Philippines and Papua New Guinea is pilinut (Canarium ovatum), in which much variation exists in kernel size and quality. Fruit pulp and kernel are edible. Melingo (Gnetum gnemon) is a dioeceous species found throughout South-East and South Asia in humid evergreen forests, but cultivation is limited to South-East Asia, more in Indonesia. Several varieties have been recognized on the basis of variation in tree habit and fruit/seed size. Kernel is eaten raw/cooked/fried. Salacca/salak (Salacca zalacca syn. S. edulis) is an important fruit of Indonesia, distributed in Java and Sumatra. Two varieties - var. zallacca distributed in Java and var. amboinensis in Bali, occur. Locally, over 20 forms are recognized, varying in fruit quality and seed size; some seedless types also occur. Other edible species are S. conferta and S. wallichiana. Much diversity occurs in Syzygium species - more diversity in S. cuminii (jamun) occurring in South Asia, particularly in India, and for S. aqueum, S. jambos, S. malaccense (Malay apple), and S. samarangense in South-East Asia. Many other species are also locally/regionally important.

In South and South-East Asia, more diversity occurs in Emblica officinalis, Zizyphus mauritiana (Indian jujube), Z. jujuba (Chinese jujube) and Tamarindus indica (tamarind) in fruit bearing, size and quality. Rich diversity occurs in jujube. In tamarind, diversity is more pronounced in South Asia, and several selections have been made, while in Emblica officinalis it is prevalent in both the regions with more variations in cultivated types in India. In India/South Asia, diversity also occurs in Grewia subinequalis, Mimusops hexandra and Carissa congesta. Sandoricum koetjape or santol of Indochinese origin has several local seedling selections/varieties grown in Thailand and the Philippines. Dialium indicum grown in Southern Thailand is a substitute for tamarind. Other less known species more confined to South-East Asia are Spondias spp., Litsea garciae, Canarium kondon, Baccaurea motleyana and B. angulata.

IPGRI's Efforts to Prioritize Genepools for Research and Development

This aspect has been discussed in detail in several papers (Arora 1995; Arora and Rao 1995) and is briefly reported below.

Assessment by ICUC

A questionnaire assessment survey in 15 countries of South, South-East and East Asia carried out by the International Centre for Underutilized Crops (ICUC) under the IPGRI-APO supported project during 1993-94 (Haq 1995) pointed out overall priorities for fruits (exotic fruits and banana excluded), such as jackfruit, mango, citrus, jujube, litchi, aonla, jamun, salak, mangosteen, rambutan, pilinut and longan (refer Table 2 for botanical names). Subsequently, it was felt that these priorities still need to be narrowed down to focus research on a few major and minor indigenous fruits, keeping in view the regional needs. Thus, IPGRI-APO organized an Expert Consultation on Tropical Fruit Species of Asia at the Malaysian Agricultural Research and Development Institute (MARDI) in May 1994, wherein regional experts from South Asia, South-East Asia and East Asia were invited to present status reports giving regional perspective on PGR activities. The deliberations of this meeting resulted in identifying the following major and minor priority fruits: Major fruits: Citrus, mango, rambutan; Minor fruits: Jack-fruit, litchi, durian. Other potential fruits identified as candidate species were litchi, mangosteen and carambola. Details on the recommendations and presentations are given in the proceedings published by IPGRI-APO (Arora and Rao 1995). Based on these recommendation, in collaboration with national programmes where active work has been going on in research and development of tropical fruits, several PGR activities have been undertaken (Arora 1995; Arora and Rao 1995). These are briefly discussed.

Information gathering and dissemination

In collaboration with the key National Programmes which hold diversity in these fruits, IPGRI-APO has brought out 21 reports on the status of genetic resources of above fruits. These reports deal with the distribution and extent of genetic diversity of cultivated and wild genepools, the status of germplasm collections, evaluation, documentation, conservation, crop improvement and utilization. The National Programme/expertise of following countries have contributed in the synthesis of such information:


Countries/National Programmes

Major fruits:


Bangladesh, India, Sri Lanka, China, Thailand, Indonesia and Philippines


India, Nepal, Sri Lanka, China and Japan


Thailand, Malaysia and Indonesia

Minor fruits:


Thailand, Malaysia and Indonesia


Bangladesh, Sri Lanka



The above 21 reports have been widely distributed by IPGRI to National Programmes and other partners in the hope that dissemination of this synthesized information will be useful in further promoting research and development needs of this region, facilitating exchange of material for better use of genetic diversity and also in developing complementary conservation strategies.

Genetic diversity studies

Rich diversity in native minor fruits assumes importance in this region as has been already discussed. Duku langsat (Lansium domesticum) is important to the socio-economy of Sumatra in Indonesia and in collaboration with the national programmes, in Western Sumatra, ecogeographic studies have been taken up and efforts are on way to collect and conserve local diversity in this fruit which is under severe threat.

Conservation strategies

Three projects are being carried out in collaboration with the National Programmes. In China, studies have been undertaken on in vitro conservation in Citrus at the Citrus Research Institute, Chongqing. As a result, 60 varieties of citrus accessions have been conserved in in vitro storage at the Institute. Another study relates to cryopreservation in mango in collaboration with the School of Biology, Zhongshan University, Guangzhou, China. Another project on cryopreservation techniques for the long term conservation of recalcitrant seeds such as of jackfruit and litchi is in progress at the National Facility for Plant Tissue Culture Repository (NFPTCR) at NBPGR, New Delhi, India. This research is primarily intended to promote within the region the adoption and use of the conservation techniques so developed.

Collaboration and networking

Some of the collaborative activities carried out by IPGRI to promote networking include the following.

Involvement with National Programmes

In the development of status reports, information gathering activities and research on genetic diversity and conservation strategies, IPGRI-APO has collaborated with more than 15 key National Institutes/organizations in South Asia, South-East Asia, East Asia, and the national expertise has been effectively utilized.

Collaboration with ICUC and UTFANET

As pointed out above, in the IPGRI funded project with ICUC during 1993-94, an information synthesis on genetic resources diversity (based on a questionnaire survey) in priority fruits of the region involving 15 countries was taken up and a database generated. The report by Dr. Nazmul Haq has since been published by IPGRI. This study also assisted in bringing out a directory of resource institutes and key scientists involved in R&D efforts in tropical fruits in the region. These reports have been subsequently distributed to key organizations by IPGRI-APO.

In the 2nd Steering Committee meeting of UTFANET held at FAO/RAPA, Bangkok, 1-2 December 1994, national priorities were determined by different participating countries, viz., India - jackfruit, mangosteen; Nepal - pummelo, jackfruit; Sri Lanka - jack-fruit, mangosteen and guava; Thailand - mangosteen, jackfruit; Bangladesh - jackfruit, pummelo; Philippines - pummelo, soursop, guava; Indonesia - jackfruit, pummelo; Vietnam - jackfruit, pummelo; Malaysia - jackfruit, guava, mangosteen. The meeting agreed that, to start with, the network will concentrate on jackfruit, pummelo and mangosteen as its priority species. IPGRI and the FAO were identified to provide a leading role in activities relating to genetic resources.

To promote further collaboration between IPGRI and UTFANET, during the Leipzig meeting in June 1996, a strong concern was expressed in collaborating on joint activities of mutual interest including consultancies, information gathering and capacity building. Also, it was agreed to work jointly on developing descriptor lists for pummelo, jackfruit and mangosteen (for a joint publication). The UTFANET Steering Committee meeting held from 13-14 April 1997 at Bangladesh Agricultural Research Institute (BARI), Dhaka, Bangladesh further stressed collaboration with IPGRI in research and development of the three priority crops of UTFANET for the nine national programmes in South and South-East Asia; UTFANET emphasis will be on: (1) genetic resources and improvement, (2) production and propagation and post-harvest technology, and (3) documentation, information. Three national programmes will develop specific projects on jackfruit (Bangladesh), pummelo (India) and mangosteen (Philippines).

In overall perspective, IPGRI-APO looks forward to more collaboration with national programmes and develop further international linkages with the FAO, ODA, ICUC, CIRAD, CIFOR, ACIAR and other organizations to promote and coordinate conservation and use of rich diversity of tropical fruit species in the region.


Arora, R.K. 1995. Promoting Conservation and Use of Tropical Fruit Species in Asia. Pp. 19-30 in Proceedings of the Expert Consultation on Tropical Fruit Species of Asia (R.K. Arora and V. Ramanatha Rao, eds.). IPGRI Office for South Asia, Pusa Campus, New Delhi, India.

Arora, R.K. and V. Ramanatha Rao (eds.). 1995. Proceedings of the Expert Consultation on Tropical Fruit Species of Asia. Malaysian Agricultural Research and Development Institute (MARDI), Serdang, Kuala Lumpur, Malaysia, 17-19 May 1994. IPGRI Office for South Asia, Pusa Campus, New Delhi, India.

Chadha, K.L. 1995. Status report on tropical fruit species in South Asia. Pp. 45-60 in Proceedings of the Expert Consultation on Tropical Fruit Species of Asia (R.K. Arora and V. Ramanatha Rao, eds.). IPGRI Office for South Asia, Pusa Campus, New Delhi, India.

Coronel, R. E. 1995. Status report on fruit species germplasm conservation and utilization in South-East Asia. Pp. 85-102 in Proceedings of the Expert Consultation on Tropical Fruit Species of Asia (R.K. Arora and V. Ramanatha Rao, eds.). IPGRI Office for South Asia, Pusa Campus, New Delhi, India.

Haq, N. 1995. Analysis of questionnaire to select priority species for research and development in Asia. Pp. 31-44 in Proceedings of the Expert Consultation on Tropical Fruit Species of Asia (R.K. Arora and V. Ramanatha Rao, eds.). IPGRI Office for South Asia, Pusa Campus, New Delhi, India.

Kostermans, A.J.H. and S.M. Bompard. 1993. The Mangoes: Their Botany, Nomenclature, Horticulture and Utilization. IBPGR and Linnean Society of London. Academic Press, London.

Leenhouts, P.W. 1971. A revision of Dimocarpus (Sapindaceae). Blumea 19:113-131.

Singh, R.B. (ed.). 1993. Research and Development of fruits in the Asia-Pacific Region. FAO/ RAPA, Bangkok, Thailand.

Verheij, E.W.M. and R. E. Coronel. (eds.). 1992. Plant Resources of South-East Asia. No.2. Edible Fruits and Nuts. PROSEA, Bogor, Indonesia.

Wong, K.C., Ibrahim Yusof, K.G. Pearce, and D. Alau Tayan. 1991. Isau- a potential tropical longan (Dimocarpus longan) of Sarawak. Pp. 234-240 in Proceedings of National Biological Symposium III. Universiti Kebangsaan Malaysia Publication, Bangi.

Wong, K.C. 1995. Collection and evaluation of under-utilized tropical subtropical fruit tree genetic resources in Malaysia. Pp.27-38 in Fruit Production in the Tropics and Sub-tropics. Japan International Research Center for Agricultural Sciences (JIRCAS), Ministry of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki, 305 Japan.

Zheng Xueqin. 1995. Genetic resources of tropical fruit species in China. Pp. 103-111 in Proceedings of the Expert Consultation on Tropical Fruit Species of Asia (R.K. Arora and V. Ramanatha Rao, eds.). IPGRI Office for South Asia, Pusa Campus, New Delhi, India.

Suggested reading (IPGRI-APO Status Reports on Tropical Fruits)

Identification of Priority Species of Tropical Fruits for Research and Development. ICUC/IPGRI-APO, Singapore. 1994.

Status Report on Genetic Resources of Litchi in China. IPGRI-APO, Singapore. 1996.

Status Report on Genetic Resources of Jackfruit in Bangladesh. IPGRI-APO, Singapore. 1996.

Status Report on Genetic Resources of Durian: (1) Malaysia, (2) Thailand. IPGRI-APO, Singapore. 1996.

Status Report on Genetic Resources of Citrus: East Asia - China, Japan; South Asia - India. IPGRI-APO, Singapore. 1996.

Status Report on Genetic Resources of Mango: South Asia - Bangladesh, India; Southeast Asia - Indonesia, Philippines, Thailand; East Asia - China. IPGRI-APO, Singapore. 1996.

Status Report on Genetic Resources of Rambutan: (1) Malaysia, (2) Thailand. IPGRI-APO, Singapore. 1996.

Status Report on Genetic Resources of Citrus in (i) Nepal, (2) Sri Lanka. IPGRI-APO-Serdang, Malaysia, 1997.

Status Report on Genetic Resources of Jackfruit in Sri Lanka. IPGRI-APO-Serdang, Malaysia, 1997.

Status Report on Genetic Resources of Mango in Sri Lanka. IPGRI-APO-Serdang, Malaysia, 1997.

Status Report on Genetic Resources of Rambutan in Indonesia. IPGRI-APO-Serdang, Malaysia, 1997.

Status Report on Genetic Resources of Durian in Indonesia. IPGRI-APO-Serdang, Malaysia, 1997.

Genetic Resources and Breeding Patterns of Five Humid Tropical Fruit Tree Species - A.N. Rao and V. Ramanatha Rao


Almost 400 species of edible fruits and nuts are identified and used either commonly or in a limited way in different countries of South-East Asia. Nearly 90% of them are woody plants including 250 tree species that mostly produce fleshy fruits, many of them with recalcitrant seeds. Among the tree species, only about 35% are cultivated in home gardens, around the villages, orchards or plantations and the remaining 65% are in the wild. Nevertheless, the fruits from the forest trees are regularly collected, sold and used. The commonly cultivated species are about 20 in number. Fruits play an important role in the Asian society especially among the rural people. Besides meeting dietary needs, fruits are used for traditional and cultural uses like offering in temples, ceremonies, giving presents, for new years greetings, weddings, decorations and others. Many species of fruits, wild or cultivated, have medicinal value (Burkill 1966; Verheij and Coronel 1992).

Tree growth in home gardens protects the environment and improves microclimate. In spite of many varieties of fruits said to be available in the tropics, the supply of good fruits is always short and beyond the economic means of majority of the people in rural areas. Besides many species of fruit trees are either irregular or limited in their bearing and fruits available for a short period. Limited quantity or availability always increases market prices. Unlike well known cultivated fruits of temperate countries, the grower can hardly influence the yield level or the period or the duration of fruiting in tropical fruit trees. Many of them are aseasonal in the cycle of reproduction. Some comparative data have been collected in the past in different countries of South-East Asia, of the commonly cultivated species, which show wide variations confirming fluctuations in yield (Table 1). It is not easy to bring many tree species under cultivation because of the lack of appropriate knowledge, huge investments involved and unpredictable profits.

Growth phenology, floral biology, life cycle, metabolism and function, cytology and embryology, seed production, viability, and seed germination of tropical fruit trees are hardly studied which are important to analyze the causes of fruit production and yield levels that influence the market supplies and the prices. The success of tropical fruit tree cultivation achieved so far is mostly due to traditional knowledge and selection of good varieties. Except for identification, science has contributed very little for fruit tree improvement including its genetics, breeding and yield. Year to year or season to season fluctuations under given conditions need to be carefully monitored to predict good harvest and to understand the fruiting season. The variations in climatic conditions influence the fruit production. The yield level is more secure and predictable with herbaceous and shrubby species than the trees. How much energy and biomass is apportioned for flower and fruit production among fruit trees is yet to be properly understood. Tree breeding is a time-consuming exercise since tree growth involves many years before they start flowering and to check on first or second generation hybrids. Very few exceptions to all the above are mango, citrus and a few others since they are cultivated for several millennia (Anon. 1996). Annuals are better utilized than perennials but very few herbs produce good table fruits of quality and taste.

Table 1. Production fluctuations and trade value of fruits in South-East Asia. Mean annual production (in '000 t) in 1986 and 1987, and change (%) from the mean for 1980 and 1981



Penninsular Malaysia


The Philippines









































































































































































Annual export (in US$ × 1000) of fruits and nuts (fresh and preserved) for four countries.

Indonesia (1988)

Peninsular Malaysia (1988)

Thailand (1987)

The Philippines (1988)




































Source: Verheij and Coronel 1992.
Most of the trees are propagated either by seeds or grafts or cuttings of one kind or the other which enhance or limit the genetic variation and breeding patterns. Natural sexual reproduction methods of fruit trees display wide variations. Within the framework of the limitations mentioned above, the germplasm collections, their maintenance and the breeding methods of five fruit tree species, namely, Averrhoa carambola (carambola), Durio zibethinus (durian), Garcinia mangostana (mangosteen), Lansium domesticum (duku/langsat) and Nephelium lappaceum (rambutan) are discussed in this paper. All of them are important cultivated fruit tree species in humid tropical countries of South-East Asia with significant economic value and annual turnover.

Origin and Distribution

Averrhoa carambola (canambola) of Oxalidaceae is said to originate from South-East Asia as well as tropical America. The exact location of the place of origin is unknown. However, this species has been introduced to many countries both in tropics as well as subtropics of old and new worlds.

Durio zibethinus (durian) of Bombacaceae is native of South-East Asia and has many closely related species. Altogether, there are 27 species and from Malaysia 23 species of this genus are reported, six of which are edible and only Durio zibethinus is commonly cultivated. This species is also widely distributed in Sumatra, Borneo, Papua New Guinea and other neighbouring countries. Some natural populations are still present in the wild and recently it has been introduced to Australia and other neighbouring countries.

Garcinia mangostana (mangosteen) of Guttiferae is an allotetraploid hybrid with the parentage of G. hombroniana and G. malaccensis. It originated in West Malaysia where both parents are present in the wild. It is cultivated in many countries both in the new and old world.

Lansium domesticum of Meliaceae, commonly known as duku/langsat originated in western part of South-East Asia. This species is less well known when compared with other fruit tree species of the region but cultivated in many countries of South-East Asia extending to Australia, Surinam, some Pacific island countries and Puerto Rico.

Naphelium lappaceum (Rambutan) of Sapindaceae is well known in South-East Asia. The origin of this species is attributed to many countries in South and South-East Asia. It is a popular fruit species of the region and commonly cultivated in many parts of South-East Asia.

Diversity in Species and Cultivars

Due to their long history and domestication, many cultivars and varieties of each of the above species have been identified and recommended for cultivation. The cultivars are known either with common names in local language or they are given specific numbers. Three clones of A. carambola are identified in Malaysia as B2, B10 and B17. All of them have sweet nutritious and non-astringent fruits. B17 is said to produce better quality fruits than B2 and B10.

Altogether 19 cultivars of Durian are recognized in Indonesia, Malaysia and Thailand (Table 2). Chanee and Mathong and Kaan Yao are widely cultivated in Thailand. Five varieties are popular (Petruk, Sunan, Sukan, Sitokong and Simas) in Indonesia. D24, MDUR88, MDUR78 and MDUR79 are the popular varieties in Malaysia. Number of fruits produced per bunch (3-5) is better in Malaysian and Thai varieties than those in Indonesia (1-2). But the number of fruits produced per tree per year is almost double in Indonesian varieties than those in Malaysia and Thailand. Fruit size plays an important role and mediates the number of total yield. But there is plenty of scope for further improvement. In Brunei, Durio zibethinus is not very common. Fruits of three other species of Durio are commonly collected and sold. One natural hybrid (D. graveolens × D. zibethinus) with few varieties is also popular (Table 2). All these would indicate that the germplasm of durian is rich and can be made use of to produce new selections/ hybrids with better quality trees that are disease-resistant and more productive.

Table 2. Durian cultivars in South-East Asia

Cultivar name


Fruit quality

Susceptibility to Phytophthora stem canker



1. D.10




From Gombak

2. D.24




Most popular cultivar

3. D.99




Widely planted, biannual, heavy bearing, good pollinator to other cultivars

4. D.123



Yellow flesh, medium to large fruit

5. D.145




From Pahang

6. MDUR.78




Hybrid, tree small and shady, thick aril, orange, good keeping quality

7. MDUR.79




Hybrid, thick aril, fruit easy to open, aril sweet and nutty, small tree

8. MDUR.88




Cross D24 × D10, vigorous, thick aril, golden colour, sweet and nutty, stores for long

9. Suran




Cream coloured flesh

10. Sukun

Very high



Long fruit, yellowish white fruit

11. Sitokong




Yellow fruit

12. Sunan




Oblong, bright yellow flesh

13. Petruk




Fruit egg shaped, medium size, yellow flesh, difficult to open


14. DBS 806




Ellipsoidal, good quality, high edible portion

15. DES 916






16. Kob





17. Kanyo




Round, mild flavour

18. Namthong




Large fruit

19. Canee




Yellow flesh, medium to large


20. D. zibethinus is not commercially important, other species and their varieties are important

21. D. graveolens-BD2, BD4, BD7 and BD10

22. D. oxleyanus-BD30

23. D. kutejensis-BD26, BD73

24. D. graveolens x D. zibethinus BD1, BD22, BD62

Sources: Various.
Cultivars in mangosteen are very few identified by variable characters like fruit shape, colour of the pericarp, etc. For all practical purposes, mangosteen has only one clonal variety since fruits are produced parthenocarpically and seedlings produced remain true to mother type.

About 20 clones of rambutan are under cultivation in different countries of South-East Asia but they all originate from six varieties of N. lappaceum (var. lappaceum, pallens, xanthoides (restricted to Borneo), cuspidatum, eriopetalum and robustum). Recommended clones in Malaysia are R3, R134, R162 and R170; in Indonesia, Rapiah, Tankuweh and Binjai, in Thailand Rognrian and Seechompoo. The clones presently used in Philippines were introduced from Indonesia and they are very popular (Yacoob and Subhadrabandhu 1995).

More varieties of Lansium domesticum have been collected at Sri Wijaya University, Palembang, Sumatra. These are all intermediate or close relatives of the two major varieties of duku and langsat. All of them are referred by local names - Rasuan, 1105, 1089, 1092, Komering 3, 12, 17, Palembang 175, 176, 358, 561, Lonjang - 2, Bulat and Penyandigan. About a dozen more varieties are in the hold, but yet to be characterized. The good varieties in Java are Duku condek and Duku metesih. Their relationship to Sumatran varieties are yet to be ascertained. Duku and langsat are the two varieties generally recognized in Malaysia and Thailand. Many sub-varieties carry local names like Duku Johore and Duku Trengganu, etc. One seedless variety of Thailand called Longkong Norathiwat, is very popular and it is propagated by cuttings, grafting, etc. (Yacoob and Subhadrabandhu 1995). This is the best variety because of bigger size, thin skin, is easily peelable, sweet and seedless. Paete, Mindanao and Duku are the three varieties cultivated in Philippines, mostly introduced from Indonesia and Malaysia (Coronel 1983). Some of the main points on origin, distribution, habit and ecology are summarized in Table 3.

Germplasm Collections

South-East Asia is one of the richest regions for plant biodiversity in the world. Many parts of the region are yet to be properly explored to identify the plant resources. Attention was called in 1970s to the urgent need of collecting data on tropical fruit germplasm in South-East Asia and other crop species, and the need for extensive survey of fruit resources in the region was emphasized. Five countries in the region were surveyed and the data on the degree of genetic erosion of fruit tree species were compiled (Sastrpradja 1975). Information on 105 species under 29 genera of 17 families was collected, classifying the wild and cultivated species and the relative status of genetic erosion of each species. Fruit tree germplasm resources available in Malaysia and the Philippines were also reported. 39 species of major fruits, 29 of minor fruits and 49 of rare fruits were recorded for Malaysia (Loh 1975). Seasonal fruit species were cultivated on 40 000 ha of land and the non seasonal ones on 42 000 ha in Malaysia. Germplasm resources available for breeding in the Philippines included 440 accessions of plants belonging to 36 families (Valmayor and Espino 1975). The varieties present under each species were also systematically listed. The relative quality of each variety and the endemic status of many were recorded. This was the beginning of analysing the fruit germplasm in South-East Asia.

Table 3. Technical details of the five tropical fruit tree species


Origin and distribution



Growth and development


Production/ trade

Averrhoa carambola Oxalidaceae 2n=22,24 2 species

South-East Asia, Tropical America, Humid tropics Subtropics

Tree upto 5-12 m tall

Poor sandy, well drained soils. Humid and dry conditions

First flowering 2, 3 years. Flowers throughout the year. Long style self-fertile. Short style- pollen from long style. 3-4 peak periods/year. Flower to fruits, 100-150 days after anthesis. No varieties except by taste- sour and sweet. Bigger fruit varieties by selection, no hybrids

Seed, budding, marcotting, grafting, 160-500 trees per hectare

50-300 kg/tree, 14-80 t/ha/ year. Income M$46 480. Expenses 17 878 per ha after 10th year, trees last for 20-25 years. Yield 46 480 kg/ha (Malaysia) (1US$=2.5M$)

Durio zibethinus1 Bombacaceae 2n = 56 27 species

Native of South-East Asia, wild in Borneo and Sumatra, Cultivated in South-East Asia

Tree, butteressed 30-40 m tall

Rainfall 1500-2000 mm., tropical to subtropical climate, well drained light soil.

Trees prefer shade for development. Juvenile-7-12 years. Flowering late in dry season (subtropics), in tropics flowers twice a year. Flower bud to anthesis- 50-60 days. Anthesis to fruit 110 days. Clones are selected for cultivation in Malaysia Thailand and Indonesia

Seed, grafting, budding one year old in field
-Hand pollination
-Thinning of flowers and fruits Heavy bearing, Ratio-vegetative: reproductive growth. All Southeast countries have their own germplasm with or without characterization
-Superior clones selected for cultivation.

Erratic in wet tropics. More regular in Thailand. Low -3-8 t/ha/year. High -10-18 t/ha/year. 50-60 fruits/tree. 1.5-4 kg/each. 1kg = US$1.40

-Hybridization not possible, no body has tried so far.
-Very few wild populations left.
-Very little energy goes to fruit production

-Cultivars not defined

Garcinia mangostana Guttiferae 2n=56-76, 88-90, 96, 120-130, 400 species

-Mostly cultivated. G. hombroniana × G. malaccensis. Alltetraploid hybrid of above parentage. West Malaysia. South-East Asia and now spread widely to many countries
-Germplasm mostly in Thailand

Tree 6-25m tall

High temperature High humidity. Dry season-flowering.

-No true seed, false seed of nucellular origin.
-Undifferentiated seed/no polarity. Segments-seedlings
-Slow growth. Fruits in 5-7 years after planting.
-Flowering twice a year. Bud flower 25 days.
-Anthesis-fruit 120 days.
-Each tree productive 40-60 years or even more, some male trees
-No pollen, no breeding

-Seed transfer to soil 2-3 years.
-Shade required. Home garden with multicrops, mixed orchards. Grafting. -poor
-G. atrovirides- root stock fast growing
-Seed viability -fresh for seeds-83-86%, 5 day 71%, 15 days-21%-Bigger seeds germinate 100% -Root stock-Calophyllum, Cartatoxyl Garcinia sp. etc.

-Thailand 10 000 ha-67-500 t (1987).
-Malaysia 2200 ha
-27 000 t
-Fruits travel well to Japan, Europe and USA.

Lansium domesticum Meliaceae 2n=144 octaploid, x=18, 15 species

- Western part South-East Asia, Borneo
- Cultivated in many countries of South East Asia, Austarlia, Hawaii, Surinam. Puerto Rico

Tree 30 m tall. Hollow tree trunk

- Sheltered humid conditions
- Lowland prefereble upto 800 m
- Clay, organic moist soil preferred

- Langsat-Seed germination 10 days-1 month 90%
- Duku 25% after 3 months Seed undifferantiated. Poly-embryonic multiple seedlings
- Fruiting 10-15 years from seed, grafted trees 5-6 years. Fruits ripen 14-17 weeks after anthesis.
- Shade promotes better flowering and fruiting.
- Parthenocarpy is the rule Apomixis common
- No breeding possible, male sterile.
- Vertical differences common

- Seed, viable 5 weeks
-Grafting preferred
-Dysoxylum sp. provide compatible root stocks
-Seeds of langsat germinate better than duku

-Philippines 10 500 ha - 26 700 t (1987)
-Malaysia 7600ha
-71 000t
-Thailand 16 000ha
-57 000t
-langsat 7000ha-39 000t
-duku Vitamin B1 and B2
-Relationship with ants for fruit production
-Use of growth substances had moderate success

Naphelium lappaceum Sapindaceae 2n=22 30 species

Mostly South-East Asia. Some wild populations left

Tree 10-15 m Clonal trees small

Humid tropics. Good rainfall 2500 mm/year, Warm period promotes good flowering

Seedling 7-20 days. Seedling trees -5-6 years for flowering. Bud grafting -2-4-years. Flower-fruit 110-120 days. Tree dioeciou Some varieties have no ma] trees, ovary not functional, small. Hermaphodite flowers. Hfm-style never splits, ovar not functional;. Hff-ovary well developed, stamens not functional. Breeding work-yet to start.

Seedlings provide root stock. Bud grafting most common.ell

-Thailand 71 150ha
-448 500t
-Malaysia 19 500ha
-57 000t.
More seasonal in Indonesia than in Malaysia/Thailand

Table 4. Collection of fruit species maintained in South-East Asian countries (number of accessions)






































































































































Source: IBPGR South-East Asian Committee Reports 1981 and 1982; Genetic Resources of Tropical and Subtropical Fruits and Nuts. IBPGR Rome, 1986.
In 1981-1982 and 1986, IBPGR mounted several commissions to collect 10 fruits tree species in several countries to build up the genetic resources. Number of accessions collected and maintained for the four fruit species are presented. (Table 4). Even after making generous allowance for duplications, the number of accessions for durian was the highest. Mangosteen was not well collected since it was believed that all mangos-teen, irrespective of the location and climate, belong to a single clone. The collections were carefully screened and the total was very much reduced. At present, there are about 1200 durian germplasm collections, in the region about 800 of them in the Horticultural Station, Chanthaburi, Thailand. More than 100 are present in Malaysia and the rest in other countries. Field genebanks are maintained in two or three stations in each country. (Table 5). As the literature and several reports reveal only a small number of these germplasm collections are effectively used. Detailed characterization of the germplasm is yet to be completed indicating the vast amount of work that needs to be done. Two limitations for the progress of work are: (a) lack of trained manpower, and (b) limited or no funds made available to maintain the collections that are built up. New strategy needs to be planned to conserve and utilize the germplasm present in different stations.

Table 5. Germplasm collection of rambutan, durian, mangosteen and duku in South-East Asia

Fruit species

No. of institutions

Number of accessions

a) Rambutan

1. Indonesia



2. Malaysia



3. Thailand



b) Durian

1. Indonesia



2. Malaysia



3. Papua New Guinea



4. Philippines



5. Thailand



c) Mangosteen

1. Indonesia



2. Papua New Guinea



3. Philippines



4. Thailand



d) Duku/langsat

1. Indonesia



2. Papua New Guinea



3. Philippines



4. Thailand



An expert consultation meeting was held in 1994 to discuss tropical fruit species of Asia (Arora and Rao 1995). Eight activities were identified to promote conservation and use of tropical fruit species, which included:

1. Assessment of priority genepools on major and minor fruit species,
2. Gather information on diversity available,
3. Information on ethnobotanical aspects,
4. Use of local knowledge,
5. Classification of genetic diversity,
6. Develop for complementary conservation strategies,
7. In vitro conservation, and
8. Ecogeographic surveys and in situ conservation.
Recommended list of major fruits suggested for different Asian regions included:
South Asia - Mango, jackfruit, citrus, litchi.
South-East Asia - Mango, rambutan, citrus, durian, jackfruit, mangosteen.
East Asia - Litchi, citrus, mango, longan.
It was agreed to give attention to carambola also. As part of documentation needs, it was decided to get the reports prepared from different countries on the current status of genetic resources of various fruits mentioned above. Most of these status reports have been finalized and circulated in APO among the concerned national programmes.

Number of germplasm collection in Thailand for durian, mangosteen and duku are large (Table 5) and most of them are not characterized and classified. Because of the export potential, Thailand grows many varieties of these fruits but the genetic diversity of the germplasm collections of different varieties is yet to be determined. Some papers are published on quality, standardization and group characterization of Thai durian and rambutan (Yacoob and Subhadrabandhu 1995).

The germplasm collection of rambutan in Malaysia is large even though only 8 varieties are recommended for cultivation (Table 5). The fruit characteristics are well analysed and 193 clones are so far registered. Early bearing hybrids are recognized by their fruit characters. The registered clones are recommended for planting. Hybridization programme is aimed to obtain dwarf varieties that produce quality fruits in great numbers. Attempts are also made to develop varieties that are resistant to pests and diseases. Plans are made to obtain intraspecific hybrids (Rukayah Aman and Salma Idris 1996).

New information is provided regarding germplasm collections of duku/langsat (Lansium domesticum). Germplasm collections are maintained in Padang, Lempang and Palembang, all in Sumatra, Indonesia. IPGRI is supporting a research project carried out in Sri Wijaya University, Palembang. Sixteen varieties have been identified and six of them are characterized. The criteria followed for selection are fruit colour, thickness of pericarp, number of seeds produced per fruit and few vegetative characters like leaf size, shape, petiole length and others. The cytological studies have yet to be done. Germination studies and seedling characters are being studied. The duku collections in Malaysia are maintained by MARDI and in a few other small gardens. The varieties are yet to be properly characterized. As part of IBPGR collection activity, some germplasm was collected nearly 15 years ago and it is maintained at Songkla University in Thailand. Three varieties are recognized and they need to be properly characterized.

Reproduction and Breeding

Averrhoa spp.

Averrhoa has only two species, A. bilimbi (bilimbi) and A. carambola (carambola). Heterostyly is the common feature in the family Oxalidaceae with distyly or very rarely with tristylous forms. In carambola, flowers with long styles are self-fertile and those with short styles receive pollen from flowers with long style. Occasionally the plants produce only long or short styled flowers, or sometimes both the types of flower are produced on the same plant. More research is needed to understand the segregation and the pattern of flower biology. No hybridization work has been done. Attempts are made to cross the two species i.e. A. bilimbi and A. carambola with no success. Flowers are produced in great numbers and less than 1% of flowers set fruits. The fruit size varies even on a single tree. Much improvement has been done for selection of good varieties and their cultivation. Size and taste of fruits are the two criteria followed to select the good varieties. Seeds are used for propagation. Grafting and budding are also common (Table 4).

Durio zibethinus (durian)

Flowers are produced in clusters and in great numbers. Anthesis is in the late afternoon or early evening. Flowers last for 12-18 hours and pollination is effected by bats and bees late in the evening or early hours of the morning. Less than 1% of flowers develop into fruits. Flowers are self incompatible and cross pollination by hand has aided better fruit set. Cleistogamy is ruled out but bud pollination (pollinating unopened flowers before anthesis) has resulted in better fruit setting than by pollinating the fully opened flowers (Coronel 1983). The species is heterozygous. No hybridization has been done so for but it is suggested that the hybridization can be relatively easy since durian species in the wild are not that different from the cultivated varieties. Clonal selection technique has helped to identify genetic variability and the selection of improved cultivars. By selection process, even the size of cultivated trees have been moderated to 15-20 m instead of 20-40 m. The branches are close together and canopy is compact in the selected cultivars. Very little work has been done on the reproductive biology of plants but good varieties that produce quality fruits are well selected and cultivated. There is no comparative study on the various varieties to match them with the agroecological conditions. The differences noted between the varieties are not very significant and it is possible that a sub-variety of one country is identified as a major variety in another country. Collecting and growing all the varieties together in a specific site or center will help to identify and select superior plants even from among the existing well established varieties. Seeds are rarely used for propagation. Grafting is more commonly practised. Hypocotyl is fleshy with abundant cambial activity and shoot tips of superior trees are grafted to hypocotyls. Under in vitro conditions, shoots developed from seedling nodes and they were rooted giving rise to plantlets. Somatic embryogenesis was also established (Goh 1997).

Gracinia mangostana (mangosteen)

It is a very popular fruit of the tropics. Genus Garcinia has about 300-350 species. Details of 24 species that occur in India, Andaman, Nicobar Island, Myanmar, Thailand, Malaysia, Philippines and Indonesia are well described. All the species of Garcinia are useful in one way or the other since they yield valuable timber, medicine, resin oil, latex (pigment), fodder and edible fruits. Most of them have sour fruits, except for mangos-teen. The sour fruits replace tamarind in the local cooking and acidity is reduced after boiling. Many believe that G. mangostana is a hybrid between G. hambroniana and G. malaccensis. The trees of the former are very much like mangosteen and still present in the wild, whereas trees of G. malaccensis are comparatively rare to find.

Details recorded by all the earlier workers suggest that mangosteen trees that are presently cultivated may represent a single clone of female trees that produce fruits parthenocarpically. The embryo is undifferentiated, seed size varies even within a single fruit, 1-3 carpels produce seeds and the others remain abortive in a five carpelled ovary. The relative role of integuments and nucellus that produce the edible flesh is yet to be well defined. Details of seed development that have been described so far raises more questions and doubts than providing the proper development details. Only two or three good papers are published on the subject and the critical points of development still remain very vague.

G. mangostana is self fertile but male sterile. Since it has many related species which are fully fertile, hybridization is possible, especially with closely related species like G. hambroniana. Intensive, well planned studies will yield good results. Another possibility is to use the tissue culture methods since tissue regeneration and differentiation in vitro is very easy to accomplish in this species. Even the embryonal tissues display great potential for proliferation and mass propagation. Cytologically, the species is very heterogenous indicating the existence of several viable but highly evolved populations. They need to be properly analyzed to unravel the genetic complexity of the species. Populations of mangosteen in different countries are not comparatively well studied. Such studies will help to understand the biodiversity of the species further substantiating the clues provided by varied diploid chromosome numbers. Multidisciplinary research will provide the key for hybridization and to improve the quality of fruits of mangosteen as well as the yield.

True to type seedlings can be obtained since undifferentiated seeds are formed in mangosteen by maternal tissues. Furthermore, each seed has the potential to give rise to 4-8 seedlings when the seed is cut transversely and the segments used. Whole seeds are also used in nurseries and more than one seedling/per seed is obtained. Very interesting results have been obtained with regard to seed size, percentage germination and seedling survival (Coronel 1983). Leaf, stem and cotyledon tissues both from juvenile and mature plants proliferated and gave rise to shoots in vitro. On separation, they could be rooted well, producing plantlets in large numbers. Both axillary and adventitious bud formation was common. The plantlets produced in vitro maintain clonal purity since no abnormal tissues or polyploid tissues were involved (Rao et al. 1982; Rao and Lee 1986; Goh et al. 1988, 1990; Goh 1997).

Lansium domesticum (duku/langsat)

It is a polymorphic species. The reproductive and vegetative characters are very similar but two or three distinct fruit types are present. The fruits of different varieties vary considerably in colour, texture, shape, taste, number of seeds produced, etc. This species is male sterile since pollen development is irregular. Polyspores (clusters of abortive pollen) are formed instead of regular pollen. Parthenocarpic fruits develop and each fruit will have 1-3 seeds. One particular variety in Southern Thailand produces no seeds at all. The plants are propagated by using seeds, when they are available and by vegetative methods like budding, grafting and others when there are no seeds. L. domesticum has many varieties and some are characterized. Large populations in different countries need to be well analysed to select superior plants. Commercial possibilities are many but presently the fruits are used mostly locally and to some extent in the region.

Since no pollen is produced, the flowers are male sterile but self fertile at least in the two major varieties. The stigma is receptive and it is possible to start hybridization trials by using the pollen of other species of Lansium. At present, there is no data available with regard to three other species of this genus.

Like mangosteen, the vegetative and reproductive tissues of this species respond positively under in vitro conditions showing proliferation, differentiation and organogenesis. But manipulating the tissue growth or by inducing somatic embryogenesis, it is possible to improve the quality of plants and fruits. In both varieties of Lansium domesticum, namely, langsat and duku, enhanced axillary branching was induced under in vitro from nodal explants of seedlings as well as mature trees (Tham 1997). Nephelium lappaceum (rambutan)

It is the only species more commonly cultivated than others. Nephelium has 30 species, very evenly distributed in Indonesia, Malaysia, Thailand and Philippines. More genetic diversity is present in the first two countries and the collection of germplasm is not complete. Even those varieties collected in 1981-82 or 1986 are not property maintained due to lack of adequate funds. Field germplasm maintenance is expensive and labour intensive. Maximum diversity is present in northern and central Borneo. It is not uncommon to find a series of intermediate forms between the wild, semi-wild (small fruits, sour) and cultivated varieties and the well recognized clones under cultivation (big fruits, firm crunchy flesh and sweet) which indicates the fact that large genepool that is present is yet to be properly improved by further hybridization. Once cultivated for a few years and later abandoned, trees revert back to wild state showing many intermediate stages between the wild and cultivated types. Fruit size, taste, good peeling and non-stringy nature of aril are the important criteria to distinguish the superior varieties.

There is no breeding work done so far in rambutan. Flower biology is studied by one or two persons and the results are inconclusive. The sexuality of flowers is interesting since a single tree produces the functionally male or female flowers or occasionally both the types of flowers on the same tree. Natural barriers created to avoid self pollination are many including the phenomenon of protandry and protogyny in a modified form. The variation in the length of style and spreading of stigma controls the self pollination process in many instances. Large number of flowers are produced in an inflorescence and less than 2% of flowers are pollinated and only 0.3-0.2% of the pollinated flowers develop into fruits (Coronel 1983). It is very common to see one small abortive fruit attached to a well developed one suggesting that one fruit perhaps develops at the expense of the other in terms of energy transfer and material accumulation. Up to end of one or two weeks after pollination, both the fruits develop simultaneously but later, one stops growing while the other continues to develop to maturity. All these details would indicate that intensive studies are required to improve our knowledge on hybridization and fruit production in rambutan. Seeds are still used for propagation in many countries. Budding is more common in many nurseries. Tissue culture protocol is available to raise plantlets using vegetative tissues of mature plants. The production of good fruits of selected varieties can be maintained by planting the in vitro raised plants on a large scale.

Outlook for the Future

Only recently rambutan was classified under major tropical fruits of the South-East Asian region. Durian, mangosteen, duku and star fruit is grouped under minor fruits (Arora and Rao 1995). The relative ranking of each and the extent of cultivation varies from country to country. However, the five fruits discussed presently are not usually consumed or traded outside the region but they have a big commercial potential. Only recently, carambola produced in Malaysia is sold regularly in Holland because of increased and regular supply as well as establishment of dependable marketing channels. Good production strategies are yet to be established for the five species discussed.

The cultivation and improvement of a fruit tree species passes through several stages, namely: (a) collecting from wild or the forest (b) domesticating and growing them in a limited way around homes or gardens and selecting the better varieties or clones (c) establishing small orchards after recognizing their economic potential, and (d) finally cultivating the select and superior varieties on large scale in a plantation with good investment and for handsome economic benefits.

The five fruit tree species discussed in this paper have not reached the plantation levels as banana, citrus or mango have. Most of them are limited to semi-wild conditions or home gardens or small orchard systems. Number of plants cultivated per hectare are small in case of durian and mangosteen, slightly better in case of rambutan and star fruit in that order. Both the area and number of plants cultivated there involves considerable manpower, investments and marketing strategies.

The volume of the total annual production of durian, mangosteen, duku, rambutan and carambola in the region is less than 50% of the total banana production which reflects the limited level of cultivation of the five species. Many improvements need to be made for further advancement. Research and development activities in the following areas are of utmost importance and to be pursued on a priority basis to improve the fruit tree species. A good knowledge of reproductive biology, phenology, vegetative propagation including tissue culture and breeding methods should be well studied. Matching the selected varieties with well identified agroecological conditions would improve the yield. By nature, most of the plants of the five species are well adapted to moist soils, good rainfall and high humid conditions.

The extent of genepool available, and germplasm collected and stored for each of the five species is variable. Selection done to establish cultivars in duku is still at preliminary stage. The collections made for durian, rambutan and mangosteen are fairly extensive. For star fruit, there is limited scope. However, the number of species or varieties used under each genus is very limited and offers good opportunity for further expansion.

Clonal propagation methods used presently are to be streamlined for all of them which would reduce the juvenile period and hasten the onset of reproductive phase. Precise details need to be recorded in each case. Flowering pattern and period of different species vary locally and in the region. Both the early and late flowering varieties need to be identified, selected and properly cultivated to prolong the fruiting season and availability. The plants that flower regularly and abundantly in a population deserve more attention to enrich the germplasm collection.

Position of inflorescences and number of fruits produced per inflorescence varies among the five species. Durian and duku are cauliflorous with limited fruit production compared with the general biomass of the tree. Though with axillary inflorescences, mangosteen is shy bearer and produces small number of fruits. Fruits of rambutan and star fruit are produced in relative large numbers. There is plenty of scope for research to increase fruit production in each of the species.

Sexuality is an enigma in both rambutan and duku. Anthesis and the correct stage of pollination and pollinators involved are to be precisely determined in each case. Fruit production method is asexual and abnormal in case of mangosteen and duku. Many gaps need to be filled for proper understanding of their reproduction.

Tree breeding is a long process in case of tropical fruit trees but a beginning has to be made to achieve success. Pioneer work already done on oranges or apples should set the guideline to plan further research. The limited manpower and finance available in the region set limitations to conduct research and in the development of facilities.

Part of the economic gains presently accrued in fruit industry should be set apart for research and development activities.

Lastly, it is important to remember that most of the fruits of these five species are sold in village markets, weekly markets or in roadside stalls, the common shopping areas of the poor people in rural areas. Any improvement planned or extended should be for the benefit of rural communities because they have been the custodians of the germplasm for long time which the researchers plan to use presently to improve the quality of trees and the quantity of fruits produced therefrom. The indigenous knowledge should be tapped to plan further activities for improvement of less well known tropical fruit tree species.


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