Why are the seeds of this species difficult? The seeds may have physiological dormancy, which can be overcome with a pre-chill treatment. Wild-growing sub-species may produce a high proportion of empty seeds, which collectors and curators must take account of.
Sorghum bicolor (Image: S. Wood, RBG Kew)
This species has Orthodox seeds - dry to 15-20% eRH and store at -20ºC, or as cool as possible.
Germinate on agar, germination paper or sand at a constant temperature of 25ºC, or under an alternating temperature regime of 30/20ºC (with an 8/16hr photoperiod). Perform a cut-test on any seeds that have not germinated, to check for empty seeds. All empty seeds are non-viable in germination tests.
The seeds of this species may be Physiologically Dormant. If germination is low, use a moist pre-chill treatment (e.g. 5 or 10ºC for 5 days) before germinating the seeds at their optimum temperature.
The occurrence of empty seeds is common in wild-collected accessions of this species. Empty seeds may have a normal seed coat but an absent or under-developed embryo, or limited storage tissue.
Sorghum bicolor section
(Image: S. Wood, RBG Kew)
Accepted name: Sorghum bicolor (L.) Moench
Synonyms: Holcus bicolor L., Sorghum vulgare subsp. bicolor (L.) Maire & Weiller, Andropogon sorghum (L.) Brot., Sorghum vulgare Pers., Sorghum membranaceum Chiov., Andropogon sorghum subsp. sativus Hack., Sorghum halepense subsp. sativum (Hack.) Trab.
Common name: sorghum, great millet
References and Links
- Black, M., Bewley, J.D. and Halmer, P. (2006). The Encyclopaedia of Seeds: science, technology and uses. CAB International, UK.
- Food and Agriculture Organization of the United Nations and International Plant Genetic Resources Institute (1994). Genebank Standards. FAO/IPGRI, Rome, Italy.
- International Seed Testing Association (2010). International Rules for Seed Testing: edition 2010. ISTA, Bassersdorf, Switzerland.
- Rao, N.K., Hanson, J., Dulloo, M.E., Ghosh, K., Nowell, D. and Larinde, M. (2006). Manual of seed handling in genebanks. Handbooks for Genebanks No. 8. Bioversity International, Rome, Italy.
- AFPD (African Flowering Plants Database) - Conservatoire et Jardin Botaniques de la Ville de Genève, Switzerland, and South African National Biodiversity Institute, Pretoria, RSA: Sorghum bicolor.
- PROTAbase (Plant Resources of Tropical Africa) - Wageningen, Netherlands: Sorghum bicolor.
- SID (Seed Information Database) - Royal Botanic Gardens, Kew, UK: Sorghum bicolor.
- Tropical Forages - CSIRO, DPI&F(Qld), CIAT and ILRI, Brisbane, Australia: Sorghum bicolor (perennial).
- Tropicos - Missouri Botanical Garden, USA: Sorghum bicolor.