Effect of Different Seed Priming Methods on Germination, Seedling Establishment and Vigour in Sorghum (Sorghum bicolor (L.) Moench.) and Bambara Groundnut (Vigna subterrenea (L.) Verdc.)

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Two experiments were designed to study the effect of hydro- priming (water) and osmo-priming (Mannitol and NaCl at -1.5 M Pa) and seed size on germination, seedlings establishment, vigour and biomass at maturity of three varieties of Sorghum bicolor L. Moench and Vigna subterrenea L. Verdc. The experiments were (1) a laboratory test with seeds germinated in wet sand for 10 days in a completely randomized design with four replications to determine germination traits, shoot and root lengths and (2) a field experiment in a Randomized Complete Block Design with three replications at the Savanna Agricultural Research Institute from August 2011 to January 2012. Seeds of three varieties of sorghum, ‘Dorado’, ‘Kapaala’ and ‘Kadaga’ were primed with Mannitol and NaCl (-1.5 M Pa) for 72 hours at 25° C and also in water for 24 h at 28 ± 3°. Large and small seeds of three varieties (‘Cream with black eye’, ‘Cream with brown eye’ and ‘Red’) of Bambara groundnut were separately primed with Mannitol and NaCl (-1.5 M Pa) for 120 h at 25° C and also primed in water separately for 24 h at 28 ± 3°. The laboratory results showed that osmo-priming of sorghum and Bambara significantly improved germination percentage, germination index, and mean germination time and seedling vigour, compared to other seed treatments. Likewise hydro-priming significantly improved seedling dry weight as compared to other seed treatments. The field results of the Bambara groundnut also showed that osmo-primed seeds had the least average delay (lag period) from the start of imbibitions to radicle emergence, were the earliest to start to germinate, obtained higher number of pods per plant in comparison with the other seed treatments. Hydro-priming significantly increased the number of plants per plot compared to other seed treatments. Seed biomass had effect on the overall percentage and seedling vigour. In all Bambara groundnut varieties, the smaller seeds had the faster germination, the higher percent germination and seed vigour. On the contrary, plants grown from large seeds produced greater dry matter compared to those grown from small seeds for all varieties.
A Thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi in partial fulfillment of the requirements for the degree of Master of Science in Seed Science and Technology,