The Compositae comprise about 20000 species of herbaceous plants in more than 800 genera which provide oils (e.g. Guizotia abyssinica (L. f.) Cass., niger), leaf vegetables (e.g. Lactuca sativa L., lettuce), edible tubers (e.g. Helianthus tuberosus L., Jerusalem artichoke) and other products (e.g. Chrysanthemum cinerariaefolium (Trev.) Bocc., pyrethrum). The seeds are achenes (see Chapter 3, Volume I) and show orthodox storage behaviour.
SEED DORMANCY AND GERMINATION
In most genera the seeds normally exhibit dormancy, but the problem this poses when attempting to promote seed germination varies considerably between both species and accessions. Light, pre-chill, potassium nitrate and temperatures around 15°C tend to promote germination. The seeds are non-endospermic and B.R. Atwater classifies the Compositae as a unique morphological category, viz: axile foliar embryos with fibrous seed coat and spearate inner semi-permeable membranous layer (see Table 17.2, Chapter 17).
Detailed information on seed dormancy and germination is provided in this chapter for the genera Carthamus, Cichorium, Guizotia, Helianthus, Lactuca and Parthenium. In addition, Table 30.1 provides a summary of germination test procedures and dormancy-breaking treatments for very many other species and the algorithm below may be helpful in developing germination test procedures for species where no advice is provided here and for difficult accessions where the regimes summarised in Table 30.1 are unable to promote full germination.
RBG Kew Wakehurst Place algorithm
The first step in the algorithm is to test three samples of seeds at constant temperatures of 11°C, 16°C and 26°C with light applied for 12h/d.
If none of these regimes is successful in promoting full germination then the second step of this algorithm is to test a further sample of seeds at a constant temperature of 6°C with light applied for 12h/d if the greatest germination occurred at 11°C in step one, or to test a further sample of seeds at a constant temperature of 21°C with light applied for 12h/d if the greatest germination occurred at 16°C or 26°C in step one. If there was little difference in germination between tests at the three constant temperatures (step one) then test two further samples of seeds at 6°C and 21°C with light applied for 12h/d.
If any of the regimes applied in the second step does not promote full germination then the third step of the algorithm is to test a further sample of seeds at an alternating temperature of 23°/9°C (12h/12h) with light applied for 12h/d during the period spent at the upper temperature of each cycle if the second step was to test at 6°C or, where two regimes were used in step two, the greatest germination was observed at 6°C. Otherwise take two further samples of seeds and test in alternating temperatures of 23°/9°C (12h/12h) and 33°/19°C (12h/12h) with light applied for 12h/d during the period spent at the upper temperature of each cycle.
If any of the regimes applied in the third step of the algorithm does not promote full germination then the fourth step of the algorithm is to pre-chill a further sample of seeds at 2° to 6°C for 8w: the subsequent germination test regime is that judged most suitable from a comparison of the results of the previous steps of the algorithm.
If the additional treatment of pre-chilling does not result in full germination then the fifth step of the algorithm is to take a further three samples of seeds, chip the fibrous seed coats and test in the most promotory regime determined in the previous steps (this may include a pre-chill treatment if the fourth step resulted in an increase in germination over previous steps) with GA3 co-applied in the germination test substrates at three concentrations, viz: 3 x 10-4 M, 7 x 10-4 M, and 2.6 x 10-3 M. Some experimentation with these conditions may be helpful. For example, if a trend in the results at different GA3 concentrations is apparent it may be worthwhile investigating the response of germination to a more extreme concentration; or chipping plus pre-chill may be sufficient to promote germination without a GA3 treatment.
If full germination has not been promoted, the sixth step of the algorithm is to estimate viability using a tetrazolium test (see Chapter 11, Volume I).
If the result of the tetrazolium test indicates that the failure to achieve full germination is due to the presence of dead seeds and that one of the above regimes promoted the germination of all, or almost all, the viable seeds, then this regime is used for all subsequent germination tests. If, however, the result of the tetrazolium test indicates that dormancy has not been broken by the regimes applied so far in the algorithm, then experiment with modifications to the above regimes. Clues to possible satisfactory dormancy-breaking treatments and promotory germination test environment can be obtained from the information provided for six genera in this chapter, from Table 17.2 (Chapter 17) and the long list of dormancy-breaking treatments in Table 30.1.
TABLE 30.1 Summary of germination test recommendations for species within the Compositae
|
Species and Authority |
Substrate |
Temperature |
Duration |
Additional directions |
Source |
|
Achillea clavennae L. |
TP; BP |
20°/30°C; 20°C |
14d |
light |
ISTA |
|
Achillea filipendulina Lam. |
TP; BP |
20°/30°C; 20°C |
14d |
light |
ISTA |
|
Achillea millefolium L.
|
TP |
20°/30°C |
14d |
|
ISTA |
|
TP |
20°/30°C |
|
|
M&O |
|
|
Achillea ptarmica L.
|
TP; BP |
20°/30°C; 20°C |
14d |
light |
ISTA |
|
TP |
20°/30°C |
10d |
light, check for empty seeds |
AOSA |
|
|
|
20°/30°C |
14d |
|
Atwater |
|
|
Ageratum houstonianum Mill.
|
TP |
20°/30°C; 20°C |
14d |
|
ISTA |
|
TP |
20°/30°C |
7d |
|
AOSA |
|
|
|
20°/30°C |
10d |
|
Atwater |
|
|
Agoseris grandiflora |
TP |
15°C; 20°C |
|
|
M&O |
|
Amberboa moschata (L.) DC.
|
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
TP |
15°C |
21d |
|
AOSA |
|
|
Ambrosia artemsifolia |
TP |
20°/30°C |
|
light |
M&O |
|
Ammobium alatum R. Br. |
TP; BP |
20°/30°C; 20°C |
14d |
|
ISTA |
|
Anthemis tinctoria L. Kelwayi |
TP |
15°C |
14d |
light, avoid temperatures above 15°C |
AOSA |
|
Anthemis sancti-johannis Turrill |
TP |
15°C |
14d |
light, avoid temperatures above 15°C |
AOSA |
|
Arctium lappa L. |
BP |
20°/30°C |
14d |
|
AOSA |
|
Arctium minus Schk. |
TP |
23°/30°C |
28d |
|
R&S |
|
Arctotis stoechadifolia Bergius |
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light |
ISTA |
|
Var grandis (Thunb.) Less
|
TP |
15°C |
18d |
check for empty seeds |
AOSA |
|
|
15°C |
21d |
|
Atwater |
|
|
Artemisia absinthium L.
|
TP |
20°/30°C |
21d |
|
ISTA |
|
TP |
20°/30°C |
14d |
|
Heit |
|
|
Artemisia dracunculus L. |
TP |
20°/30°C |
21d |
|
ISTA |
|
Artemisia maritima L. |
TP |
20°/30°C |
21d |
|
ISTA |
|
Artemisia vulgaris L.
|
TP |
20°/30°C |
21d |
|
ISTA |
|
|
20°C |
14d |
|
Atwater |
|
|
Aster alpinus L. |
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
Aster amellus L. |
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
Aster canescens |
TP |
15°C |
|
light |
M&O |
|
Aster dumosus L. |
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
Aster glaucoides (Nutt.) Elliot |
|
20°C |
5d |
excise embryos |
Atwater |
|
Aster spp. |
TP |
20°/30°C |
|
light |
M&O |
|
Baccharis spp. |
|
20°C |
10d |
|
Atwater |
|
Baileya multiradiata Torr. |
TP |
20°/30°C |
14d |
light, if seeds infected then treat |
AOSA |
|
Balsamorhiza sagittata (Pursh.) Nutt. |
|
20°C |
5d |
excise embryos |
Atwater |
|
Bellis perennis L.
|
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
TP |
20°/30°C |
6d |
light |
AOSA |
|
|
|
20°C |
14d |
|
Atwater |
|
|
Brachycome iberidifolia Benth.
|
TP |
20°/30°C; 15°C |
14d |
|
ISTA |
|
TP |
15°C |
12d |
avoid temperatures above 15°C |
AOSA |
|
|
Buphthalmum salicifolium L. |
TP |
20°/30°C |
14d |
light |
AOSA |
|
Calendula officinalis L. |
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
TP |
20°C |
10d |
potassium nitrate, test at 15°C |
AOSA |
|
|
|
15°C |
14d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Callistephus chinensis (L.) Nees
|
TP |
20°/30°C; 20°C |
14d |
light |
ISTA |
|
TP |
20°C |
8d |
fungicide treatment may be necessary |
AOSA |
|
|
|
20°C |
14d |
|
Atwater |
|
|
Castalis tragus (Ait.) Norl. |
TP; BP |
20°/30°C; 15°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
Centaurea americana Nutt.
|
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill, pre-soak, 24h |
ISTA |
|
BP |
20°/30°C |
14d |
clip radicle end of seed, extend test for 5d |
AOSA |
|
|
|
20°/30°C |
28d |
|
Atwater |
|
|
Centaurea cineraria L.
|
TP |
15°C |
21d |
|
AOSA |
|
|
15°C |
21d |
|
Atwater |
|
|
Centaurea cyanus L. |
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
TP |
15°C |
8d |
fungicide treatment may be necessary |
AOSA |
|
|
|
15°C |
14d |
|
Atwater |
|
|
Centaurea dealbata Willd. |
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Centaurea diffusa |
TP |
20°/30°C |
|
|
M&O |
|
Centaurea gymnocarpa Moris & DeNot.
|
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
TP |
15°C |
16d |
|
AOSA |
|
|
|
15°C |
21d |
|
Atwater |
|
|
Centaurea imperialis Bornm.
|
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
TP |
15°C |
16d |
|
AOSA |
|
|
|
15°C |
21d |
|
Atwater |
|
|
Centaurea macrocephala Puschk. ex Willd. |
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Centaurea montana L. |
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Centaurea ragusina L. |
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Centaurea solstitialis |
TP |
20°/30°C; 15°C; 20°C |
|
light |
M&O |
|
Chrysanthemum carinatum Schousb.
|
TP; BP |
20°/30°C; 15°C |
21d |
light, pre-chill |
ISTA |
|
TP |
15°C |
10d |
check for empty seeds |
AOSA |
|
|
Chrysanthemum coronarium L.
|
TP; BP |
20°/30°C; 15°C |
21d |
light, pre-chill |
ISTA |
|
TP |
15°C |
10d |
check for empty seeds |
AOSA |
|
|
Chrysanthemum multicaule Desf. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Chrysanthemum nivellei Br.-Blanq. & Maire |
TP; BP |
20°/30°C; 20°C |
21d |
pre-chill |
ISTA |
|
Chrysanthemum ptarmiciflorum (Webb) Brenan |
TP |
15°C |
12d |
light, fungicide treatment may be necessary |
AOSA |
|
Chrysanthemum segetum L. |
TP; BP |
20°/30°C; 15°C |
21d |
pre-chill |
ISTA |
|
TP |
15°C |
10d |
check for empty seeds |
AOSA |
|
|
Chrysanthemum spp. |
|
20°C |
14d |
|
Atwater |
|
Chrysopsis spp. |
|
20°C |
5d |
excise embryos |
Atwater |
|
Chrysothamnus nauseosus (Pall.) Britt. |
|
20°C |
14d |
|
Atwater |
|
Cirsium vulgare |
TP |
20°/30°C |
|
|
M&O |
|
Cnicus benedictus L. |
TP; BP; S |
20°/30°C |
21d |
pre-chill |
ISTA |
|
Coreopsis basalis (Otto & A. Dietr.) Blake |
TP |
20°C |
8d |
|
AOSA |
|
Coreopsis cardaminifolia (DC.) Nutt. |
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
Coreopsis coronata L. |
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
Coreopsis drummondii Torr. & Gray |
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
Coreopsis lanceolata L.
|
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C; 15°C |
21d |
light, potassium nitrate |
AOSA |
|
|
|
20°/30°C; 15°C; 20°C |
40d |
potassium nitrate, 0.2% |
Atwater |
|
|
Coreopsis maritima (Nutt.) Hook. f. |
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
Coreopsis tinctoria Nutt.
|
TP |
20°/30°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
20°C |
8d |
|
AOSA |
|
|
Cosmos bipinnatus Cav. |
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C |
8d |
light, potassium nitrate, extend test period |
AOSA |
|
|
|
20°/30°C |
14d |
test at 15°C |
Atwater |
|
|
Cosmos sulphureus Cav.
|
TP; BP |
20°/30°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C |
8d |
light, potassium nitrate |
AOSA |
|
|
|
20°/30°C |
14d |
test at 15°C |
Atwater |
|
|
Crepis capillaris |
TP |
20°/30°C; 15°C |
|
light |
M&O |
|
Cynara cardunculus L.
|
BP; S |
20°/30°C |
21d |
|
ISTA |
|
BP |
20°/30°C |
21d |
|
AOSA |
|
|
Cynara scolymus L.
|
BP; S |
20°/30°C |
21d |
|
ISTA |
|
BP |
20°/30°C |
21d |
|
AOSA |
|
|
TP |
20°/30°C |
21d |
|
Fornerod |
|
|
Dahlia pinnata Cav.
|
TP; BP |
20°/30°C; 15°C; 20°C |
21d |
pre-chill |
ISTA |
|
|
15°C |
14d |
|
Atwater |
|
|
Dahlia spp. |
TP; BP |
15°C |
14d |
seeds sensitive to drying out in test |
AOSA |
|
Dendrathema indicum (L.) Desm. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Dimorphotheca pluvialis (L.) Moench |
TP; BP |
20°/30°C; 15°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
Dimorphotheca sinuata DC.
|
TP |
15°C |
10d |
light, potassium nitrate, check for empty seeds |
AOSA |
|
|
15°C |
14d |
|
Atwater |
|
|
Doronicum orientale Hoffm.
|
TP |
20°/30°C; 20°C |
21d |
potassium nitrate, pre-chill |
ISTA |
|
TP |
20°C |
21d |
light |
AOSA |
|
|
Echinacea purpurea (L.) Moench
|
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
TP |
20°/30°C |
12d |
light |
AOSA |
|
|
Echinops ritro L.
|
TP; BP |
20°/30°C |
21d |
|
ISTA |
|
TP |
20°/30°C |
21d |
light, good moisture supply |
AOSA |
|
|
Encelia californica Nutt. |
|
20°C |
5d |
excise embryos |
Atwater |
|
Encelia farinosa Gray |
|
20°C |
5d |
excise embryos |
Atwater |
|
Erigeron speciosus (Lindl.) DC. |
TP |
20°/30°C; 20°C |
28d |
|
ISTA |
|
TP |
15°C |
16d |
light |
AOSA |
|
|
Eriophyllum confertiflorum (DC.) Gray |
|
20°C |
5d |
excise embryos |
Atwater |
|
Eriophyllum lanatum Forbes |
TP |
20°/30°C |
|
|
M&O |
|
Gaillardia aristata Pursh.
|
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
TP |
20°/30°C |
10d |
light, check for empty seeds |
AOSA |
|
|
TP |
20°/30°C |
|
light |
M&O |
|
|
|
20°/30°C |
14d |
|
Atwater |
|
|
Gaillardia pulchella Foug.
|
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
TP |
20°/30°C |
10d |
light, check for empty seeds |
AOSA |
|
|
|
20°/30°C |
14d |
|
Atwater |
|
|
Gazania rigens (L.) Gaertn. |
TP; BP |
20°/30°C; 15°C |
21d |
pre-chill |
ISTA |
|
TP |
15°C |
12d |
check for empty seeds |
AOSA |
|
|
|
15°C |
21d |
|
Atwater |
|
|
Gerbera jamesonii Hook. f. |
TP |
20°/30°C; 20°C |
14d |
|
ISTA |
|
TP; BP |
20°/30°C; 20°C |
10d |
light |
AOSA |
|
|
|
20°/30°C |
14d |
|
Atwater |
|
|
Gnaphalium microcephalum |
TP |
15°C |
|
light |
M&O |
|
Grindelia stricta DC. |
|
20°C |
14d |
excise embryos |
Atwater |
|
Helenium autumnale L. |
TP; BP |
20°/30°C; 20°C |
14d |
|
ISTA |
|
Helenium spp. |
TP |
20°/30°C |
16d |
light, check for empty seeds |
AOSA |
|
Helichrysum bracteatum (Vent.) Andr.
|
TP; BP |
20°/30°C; 15°C |
14d |
light, potassium nitrate, pre-chill |
ISTA |
|
TP |
15°C |
10d |
light, potassium nitrate |
AOSA |
|
|
Heliopsis helianthoides (L.) Sweet |
TP; BP |
20°/30°C |
21d |
potassium nitrate, pre-soak, 24h |
ISTA |
|
Heliopsis spp. |
TP |
20°/30°C |
18d |
|
AOSA |
|
Helipterum craspedioides |
|
|
|
excise embryos |
Atwater |
|
Helipterum humboldtianum (Gaudich.) DC. |
TP; BP |
20°/30°C; 15°C |
21d |
pre-chill |
ISTA |
|
Helipterum manglesii (Lindl.) F. Muell. |
TP; BP |
20°/30°C; 15°C |
21d |
pre-chill |
ISTA |
|
Helipterum roseum (Hook.) Benth.
|
TP; BP |
20°/30°C; 15°C |
21d |
pre-chill |
ISTA |
|
TP |
15°C |
18d |
|
AOSA |
|
|
|
20°C |
14d |
|
Atwater |
|
|
Hymenoclea salsola T. & G. |
|
20°C |
5d |
excise embryos |
Atwater |
|
Hypochaeris radicata |
TP |
20°/30°C |
|
|
M&O |
|
Inula grandiflora Willd. |
TP |
20°/30°C |
14d |
light |
AOSA |
|
Inula helenium L. |
TP |
20°/30°C; 20°C |
28d |
|
ISTA |
|
Lapsana communis |
TP |
20°/30°C |
|
|
M&O |
|
Layia platyglossa (F. & M.) Gray
|
TP |
15°C |
8d |
light, avoid temperatures above 15°C |
AOSA |
|
|
20°C |
14d |
|
Atwater |
|
|
Leontodon nudicaulis |
|
20°/30°C |
|
|
M&O |
|
Leontopodium alpinum Cass. |
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
Leucanthemum maximum Ram. DC. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Leucanthemum vulgare Lam. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Liatris pycnostachya Michx. |
TP |
20°/30°C |
28d |
|
ISTA |
|
Liatris spicata (L.) Willd. |
TP |
20°/30°C |
28d |
|
ISTA |
|
Lonas annua (L.) Vines & Druce |
TP |
20°/30°C |
28d |
|
ISTA |
|
Machaeranthera tanacetifolia (HBK) Nees |
TP |
15°C |
10d |
avoid temperatures above 18°C |
AOSA |
|
Madia exigua |
TP |
15°C |
|
|
M&O |
|
Matricaria chamomilla L. |
TP |
20°/30°C |
14d |
pre-chill |
ISTA |
|
Matricaria maritima |
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
Matricaria perforata Merat |
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
Matricaria recutila L. |
TP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
Matricaria spp.
|
TP |
20°/30°C; 20°C |
7d |
light |
AOSA |
|
|
20°C |
14d |
|
Atwater |
|
|
Osteospermum ecklonis (DC.) Norl. |
TP; BP |
20°/30°C; 15°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
Pyrethrum spp. |
TP |
15°C |
21d |
potassium nitrate |
AOSA |
|
Rudbeckia fulgida Ait. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Rudbeckia hirta L. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Rudbeckia spp. |
|
20°/30°C |
14d |
|
Atwater |
|
Sanvitalia procumbens Lam.
|
TP; BP |
20°/30°C; 20°C |
14d |
pre-chill |
ISTA |
|
TP; BP |
20°/30°C; 20°C |
7d |
light, check for empty seeds |
AOSA |
|
|
Scorzonera hispanica L.
|
TP; BP |
20°/30°C; 20°C |
8d |
pre-chill |
ISTA |
|
BP |
20°/30°C |
8d |
pre-chill, 10°C, 5d |
Fornerod |
|
|
Senecio bicolor (Willd.) Tod. |
TP |
20°/30°C; 20°C |
21d |
pre-chill |
ISTA |
|
Senecio cruentus (L'Her.) DC. |
TP |
20°/30°C; 20°C |
21d |
pre-chill |
ISTA |
|
TP |
20°C |
14d |
light |
AOSA |
|
|
|
20°C |
14d |
|
Atwater |
|
|
Senecio elegans L. |
TP |
20°/30°C; 20°C |
21d |
pre-chill |
ISTA |
|
Senecio jacobea |
TP |
15°C |
|
light |
M&O |
|
Sonchus arvensis |
TP |
20°/30°C |
|
light |
M&O |
|
Silybum marianum (L.) Gaertn. |
TP; BP; S |
20°/30°C; 20°C |
21d |
pre-chill |
ISTA |
|
Tagetes erecta L. |
TP; BP |
20°/30°C; 20°C |
14d |
light |
ISTA |
|
Tagetes patula L. |
TP; BP |
20°/30°C; 20°C |
14d |
light |
ISTA |
|
Tagetes tennifolia Cav. |
TP; BP |
20°/30°C; 20°C |
14d |
light |
ISTA |
|
Tagetes spp.
|
TP |
20°/30°C; 20°C |
7d |
light, check for broken seedlings |
AOSA |
|
|
20°/30°C |
10d |
|
Atwater |
|
|
Tanacetum achilleifolium (Bieb.) Sch. Bip. |
TP; BP |
20°/30°C; 15°C |
21d |
light, pre-chill |
ISTA |
|
Tanacetum cineraiifolium (Trev.) Sch. Bip. |
TP; BP |
20°/30°C; 20°C |
21d |
pre-chill |
ISTA |
|
Tanacetum coccineum (Willd.) Grierson |
TP; BP |
20°/30°C; 15°C |
21d |
light, pre-chill, potassium nitrate |
ISTA |
|
Tanacetum parthenium (L.) Sch. Bip. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill |
ISTA |
|
Tanacetum vulgare L. |
TP |
20°/30°C |
|
|
M&O |
|
Taraxacum erythrospermum |
TP |
20°/30°C; 15°C; 20°C |
|
light, test at 15°C |
M&O |
|
Taraxacum officinale Wigg.
|
TP |
20°/30°C; 20°C |
21d |
|
ISTA |
|
TP |
20°/30°C |
21d |
light |
AOSA |
|
|
TP |
20°/30°C; 15°C |
|
light |
M&O |
|
|
TP |
20°C |
14d |
light |
Heit |
|
|
Tithonia rotundifolia (Mill.) Blake |
TP; BP |
20°/30°C |
8d |
light |
AOSA |
|
Tragopogon porrifolius L. |
TP; BP |
20°C |
10d |
pre-chill |
ISTA |
|
BP |
15°C |
10d |
pre-chill, 10°C, 3d |
AOSA |
|
|
TP |
20°/30°C |
|
light |
M&O |
|
|
Tragopogon spp. |
BP |
15°C |
10d |
|
Everson |
|
Venidium fastuosum (Jacq.) Stapf |
TP |
20°/30°C |
10d |
light |
AOSA |
|
Viquiera laciniata Gray |
|
20°C |
5d |
excise embryos |
Atwater |
|
Xeranthemum annuum L. |
TP; BP |
20°/30°C; 20°C |
14d |
|
ISTA |
|
Zinnia acerosa (DC.) Gray |
TP; BP |
20°/30°C; 20°C |
7d |
light, check for empty seeds |
AOSA |
|
Zinnia angustifolia HBK |
TP; BP |
20°/30°C; 20°C |
7d |
light, check for empty seeds |
AOSA |
|
Zinnia elegans Jacq.
|
TP; BP |
20°/30°C; 20°C |
10d |
light, pre-chill |
ISTA |
|
TP; BP |
20°/30°C; 20°C |
7d |
light, check for empty seeds |
AOSA |
|
|
Zinnia grandiflora Nutt. |
TP; BP |
20°/30°C; 20°C |
7d |
light, check for empty seeds |
AOSA |
|
Zinnia haageana Regel |
TP; BP |
20°/30°C; 20°C |
10d |
light, pre-chill |
ISTA |
|
Zinnia peruviana L. |
TP; BP |
20°/30°C; 20°C |
7d |
light, check for empty seeds |
AOSA |
|
Zinnia spp. |
|
20°/30°C |
7d |
|
Atwater |
CARTHAMUS
|
C. alexandrius |
|
|
C. flavescens |
|
|
C. glaucus |
|
|
C. lanatus L. |
saffron thistle |
|
C. oxyacantha Bieb. |
wild safflower |
|
C. palaestinus Eig. |
|
|
C. tinctorius L. |
safflower |
I. Evidence of dormancy
Freshly harvested seeds of the cultivated safflower (C. tinctorius L.) are usually non-dormant (4,6,7,9), but seeds of the wild species, C. alexandrius, C. flavescens, C. glaucus, C. lanatus, C. oxyacantha and C. palaestinus may show considerabl e dormancy (1,3,4,6-9). For example, seeds of C. oxyacantha after-ripened for one year at 23°C gave only 33% germination despite being 82% viable (3). Seeds of the inter-specific hybrids between C. tinctorius and the wild species can also be dormant (7,9).
II. Germination regimes for non-dormant seeds
C. tinctorius
TP; BP; S: 25°C; 20°/30°C (16h/8h): 14d (ISTA)
BP; TP; S: 15°C; 20°C: 14d (AOSA)
Constant temperatures: 15°-20°C (4)
Alternating temperatures: 16°/27°C (12h/12h) (9)
III. Unsuccessful dormancy-breaking treatments
C. lanatus
Pre-soak: in dark, germinate at 25°C in dark (8)
Pre-wash: 24h with far red irradiation, 7x10-6 mol m-2 s-1 (8)
C. oxyacantha
Pre-chill: 0°C, 28d, then scarify (4); 4°C, 70d (3); 4°C, 70d, then scarify (3)
IV. Partly-successful dormancy-breaking treatments
C. lanatus
Pre-soak: 2-24h, continuous light, 10-5 mol m-2 s-1 (8); 24h, in dark, germinate at 25°C in light, 10-5, 25x10-5 mol m-2 s-1 (8); 24h, in light, 10-5 mol m-2 s-1, germinate at 25°C in dark or light, 10-5, 25x10-5 mol m-2 s-1 (8); 24h, in light, 25x10-5 mol m-2 s-1, germinate at 25°C in dark or light, 10-5, 25x10-5 mol m-2 s-1 (8)
Pre-wash: 24h, continuous light, 10-5 mol m-2 s-1 (8)
C. oxyacantha
Constant temperatures: 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, optimum at 15°-20°C, in dark (4)
Pre-chill: 0°C, 1m (4); 3°-5°C, 2-8w (3); 3°-5°C, 2-8w, then cut off tip of seed coat (3)
Removal of seed covering structures: cut off tip of seed coat (1,3,4)
Polyethylene glycol: co-applied, -1, -2 bar (2)
Pre-wash: (6)
V. Successful dormancy-breaking treatments
C. lanatus
Pre-soak: 24h, continuous light, 650 nm, 7x10-6 mol m-2 s-1, germinate at 25°C in dark (8)
C. oxyacantha
Pre-soak: 1-4d, germinate at 18°C in dark (6)
C. tinctorius
Light at 15°C (AOSA)
Constant temperatures: 15°C (5)
VI. Comment
Constant temperatures of 15°C and 20°C are suitable for the germination of seeds of C. oxyacantha and C. tinctorius (4,6). Pre-soaking the seeds in water for 24 hours promotes the germination of C. oxyacantha and C. lanatus (6,9), and does not damage seeds of C. tinctorius (6). The effect of light is very significant during both the pre-soak period and the germination test - high light intensity (25x10-5 mol m-2 s-1) being less suitable for germination than a low light intensity (10-5 mol m-2 s-1) (8).
Consequently the following germination test regime is suggested for seeds of all Carthamus spp. - including the cultivated C. tinctorius and its hybrids: pre-soak the seeds in water for 24 hours under red light (650 nm, 7x10-6 mol m-2 s-1) and test for germina tion at 15°C in the dark.
VII. References
1. Bassiri, A. and Kheradnam, M. (1976). Relationships between seed color and viability, germination and seedling growth of wild safflower ecotypes. Canadian Journal of Plant Science, 56, 911-917.
2. Bassiri, A., Khosh-Khui, M. and Rouhani, I. (1977). The influences of simulated moisture stress conditions and osmotic substances on germination and growth of cultivated and wild safflowers. Journal of Agricultural Science (Cambridge), 88, 95-100.
3. Bassiri, A. and Rouhani, I. (1976). Effect of seed treatment on germination of wild safflower. Weed Science, 24, 233-234.
4. Bassiri, A., Rouhani, I. and Ghorashy, S.R. (1975). Effect of temperature and scarification on germination and emergence of wild safflower, Carthamus oxyacantha Bieb. Journal of Agricultural Science (Cambridge), 84, 239-243.
5. Heit, C.E. (1948). Laboratory germination results with herb and drug seed. Proceedings of the Association of Official Seed Analysts, 38, 58-62.
6. Kheradnam, M. and Bassiri, A. (1980). Seed germination and seedling growth inhibition caused by safflower seed extracts. Agronomy Journal, 72, 31-35.
7. Kotecha, A. and Zimmerman, L.H. (1978). Genetics and seed dormancy and its association with other traits in safflower. Crop Science, 18, 1003-1007.
8. Wright, G.C., McWilliam, J.R. and Whalley, R.D.B. (1980). Effects of light and leaching on germination of saffron thistle (Carthamus lanatus L.). Australian Journal of Plant Physiology, 7, 587-594.
9. Zimmerman, L.H. (1972). Variation and selection for pre-harvest seed dormancy in safflower. Crop Science, 12, 33-34.
CICHORIUM
|
C. endivia L. |
endive |
|
C. intybus L. |
chicory, succory |
|
C. pumilum Jacq. |
wild chicory |
I. Evidence of dormancy
Freshly harvested seeds of C. endivia can exhibit considerable dormancy (11). Secondary dormancy may be induced if seeds of Cichorium spp. are exposed to high temperatures in the absence of light (6).
II. Germination regimes for non-dorment seeds
C. endivia
TP: 20°C; 20°/30°C (16h/8h): 14d (ISTA)
TP; TS: 20°/30°C (16h/8h): 14d (AOSA)
Constant temperatures: 20°C (11)
Alternating temperatures: 20°/30°C (16h/8h) (11)
C. intybus
TP: 20°C; 20°/30°C (16h/8h): 14d (ISTA)
TP; TS: 20°/30°C (16h/8h): 14d (AOSA)
Alternating temperatures: 20°/30°C (16h/8h) (3)
III. Unsuccessful dormancy-breaking treatments
C. endivia
Constant temperatures: 2°C (1,9); above 30°C, dark (6,9)
Potassium nitrate: co-applied, 0.1, 0.2% (11)
IV. Partly-successful dormancy-breaking treatments
C. endivia
Constant temperatures: 7°C, light, 8h/d (1)
Warm stratification: 18°C, 25°C, 4-24h, germinate at 30°C, with or without thiourea, co-applied, 0.5% (6)
C. intybus
Constant temperatures: 20°C, light (2); 15°-25°C, dark (8); 11°-25°C, light, 30 W m-2, 8h/d (10)
Alternating temperatures: 20°/30°C (18h/6h) in light (2); 20°/30°/8°C (10h/8h/6h) in light (2)
C. pumilum
Thiourea: co-applied, 0.2%, at 27°C in light (5)
V. Successful dormancy-breaking treatments
C. endivia
Potassium nitrate (ISTA)
Light, Potassium nitrate, test in soil, excess moisture for first 24h (AOSA)
Constant temperatures: 17°C, light, 30 W m-2, 8h/d (1); 13°-21°C, light, 30 W m-2, 8h/d (9)
Thiourea: co-applied, 0.5% (11)
C. intybus
Potassium nitrate (ISTA)
Light, Potassium nitrate, test in soil (AOSA)
Constant temperatures: 10°-20°C, dark (7)
Alternating temperatures: 20°/30°C (16h/8h), light (4)
VI. Comment
Although thiourea, co-applied at 0.5%, promoted the germination of dormant seeds of C. endivia (11), abnormal germination occurred (11): treatment at a lower concentration might be worth investigating. Seeds of Cichorium spp. require light (1,2,4,5,9-11) and a relatively low temperature - 10° to 25°C - (1,7-11) for germination. The seed lots used in most of the cited papers showed little dormancy. For such seed lots the ISTA/AOSA germination test procedures are satisfactory. We suggest, however, that gene banks handling more dormant accessions of Cichorium spp. should test the seeds at 15°C in light.
The amount of moisture held by the germination test substratum can be critical: excess moisture, either from the use of many layers of wetted paper or thoroughly wetted absorbent cotton, can greatly promote the germination of dormant seeds of C. endivia (11). It has been suggested that light is only promotory when applied to tests carried out in the presence of excess moisture (11). Hence the AOSA recommendations. We suggest, therefore, that where possible germination tests are carried out on thoroughly wetted absorbent cotton.
VII. References
1. Bierhuizen, J.F. and Wagenvoort, W.A. (1974). Some aspects of seed germination in vegetables. 1. The determination and application of heat sums and minimum temperature for germination. Scientia Horticulturae, 2, 213-219.
2. Cross, H. (1931). Laboratory germination of weed seeds. Proceedings of the Association of Official Seed Analysts, 24, 125-128.
3. Fornerod, C. (1975). Remarques sur la germination des semences potagères en laboratoires. Revue Horticole Suisse, 48, 6-9.
4. Heit, C.E. (1948). Laboratory germination results with herb and drug seed. Proceedings of the Association of Official Seed Analysts, 38, 58-62.
5. Moursi, M.A., Rizk, T.Y. and El-Deepah, H.R. (1977). Weed seed germination responses to some chemical treatments. Egyptian Journal of Agronomy, 2, 197-209.
6. Thompson, R.C. (1946). Germination of endive seed (Cichorium endivia) at high temperature stimulated by thiourea and by water treatments. Proceedings of the American Society for Horticultural Science, 47, 323-326.
7. Valette, R. (1978). Influence de la température sur la germination des semences de chicoreé de Bruxelles. Bulletin des Recherches Agronomiques de Gembloux, 13, 183-196.
8. Valette, R. (1981). Etude de la germination à differentes temperatures de semences de Chicoreé de Bruxelles. Revue de l'Agriculture, 34, 995-1007.
9. Wagenvoort, W.A. and Bierhuizen, J.F. (1977). Some aspects of seed germination in vegetables. II. The effect of temperature fluctuation, depth of sowing, seed size and cultivar, on heat sum and minimum temperature for germination. Scientia Horticulturae, 6, 259-270.
10. Wagenvoort, W.A., Boot, A. and Bierhuizen, J.F. (1981). Optimum temperature range for germination of vegetable seeds. Gartenbauwissenschaft, 46, 97-101.
11. Munn, M.T. (1949). Endive seed germination. Proceedings of the Association of Official Seed Analysts, 39, 122-125.
GUIZOTIA
|
G. abyssinica (L. f.) Cass. |
niger, noog |
I. Evidence of dormancy
There is little literature on niger seed germination in the literature and little evidence of dormancy.