Sorghum bicolor

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)

Seed Storage

This species has Orthodox seeds - dry to 15-20% eRH and store at -20ºC, or as cool as possible.

Germination Requirements

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.

Seed Morphology

Sorghum bicolor section
(Image: S. Wood, RBG Kew)

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.

See more images of this species at VIRBOGA (The Virtual Botanic Garden), the Digital Atlas of Economic Plants and the Digital Seed Atlas of the Netherlands.

Taxonomy

Family: POACEAE

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.