In a study to determine the response of local bambara groundnut (Vigna subterranea (L.) Verdc.) germplasm to seed enhancement, seeds were subjected to hydration (12, 75 and 93% RH) to influence pre-germination water activity (a_w) and subsequent germination and seedling establishment. This study also reports on seedling characteristics 28 days after sowing under a controlled environment at 75% field capacity. There were highly significant (P < 0.01) differences between hydration treatments. The low RH resulted in a_w ranging from 0.06, 1 h after suspension to 0.39, 72 h after suspension, whereas the 93% RH resulted in a_wranging from 0.2, 1 h after suspension to 0.68, 72 h later. Subjecting seeds to pre-germination hydration caused a significantly improved seed imbibition (P < 0.05) (up to 40%), germination (35%) (P < 0.05) and seedling establishment (P < 0.05) (as indicated by seedling size and utilization of seed storage tissue). It is concluded that the delay in seedling establishment due to lack of pre-germination hydration or low RH (12%) is linked to the observed collapse of seedling leaf stomata. Hence, the findings of this study have a bearing on drought tolerance.

Key words: Hydration, germination, seed, water activity.