Why are the seeds of this species difficult? Wild-growing sub-species may produce a high proportion of empty seeds, which collectors and curators must take account of. The seeds may have physiological dormancy, which can be overcome with a pre-chill or a dry after-ripening treatment.
Pennisetum glaucum (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 constant temperatures of 20ºC, or using alternating temperature regimes of 30/20ºC or 35/20ºC (with an 8/16hr photoperiod), depending on local climatic conditions. 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 (based on other species in the same genus). If germination is low, this type of seed dormancy can be overcome with a moist pre-chill treatment at 10ºC for 5 days or a dry after-ripening treatment at 40ºC for 5 days, before germinating the seeds on agar, germination paper or sand at their optimum temperature. If this does not work, you can perform delicate surgery to enable the embryo to grow. Excise the tissue near the root tip.
(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. 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 the Digital Atlas of Economic Plants.
Accepted name: Pennisetum glaucum (L.) R.Br.
Common name: pearl 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: Pennisetum glaucum.
- PROTAbase (Plant Resources of Tropical Africa) - Wageningen, Netherlands: Pennisetum glaucum.
- SID (Seed Information Database) - Royal Botanic Gardens, Kew, UK: Pennisetum glaucum.
- Tropical Forages - CSIRO, DPI&F(Qld), CIAT and ILRI, Brisbane, Australia: Pennisetum glaucum.
- Tropicos - Missouri Botanical Garden, USA: Pennisetum glaucum.