Effect of Hydropriming on Seedling Growth of Different Bambara Groundnut (Vigna subterranea (L.) Verdc.) Landraces

Bambara groundnut (Vigna subterranea (L.) Verdc.) is a drought-tolerant, underutilised legume with the potential to improve food security, but its slow, uneven germination due to hard seed coats constrains cultivation. This study investigated the effects of hydropriming (0, 12, 24, and 36 h) on the seed imbibition, emergence, and early seedling growth in four landraces (NW, Nov4, ARC, and 519) under greenhouse conditions. The results showed genotype-specific variation in the water uptake, with Genotype 519 exhibiting the highest water imbibition (17.31%) at 36 h, while NW displayed slower but steadier hydration (13.51%). These differences reflect contrasting seed coat permeability and hydration strategies, which influenced the subsequent emergence patterns. Hydropriming significantly reduced the time to emergence (50% emergence by Day 5 in NW) and increased the seedling vigour. After 9 days of growth, the shoot length increased from 7.8 cm to 12.7 cm, the root length from 11.6 cm to 18.1 cm, and the dry mass from 0.38 g to 0.67 g. Analysis of variance (ANOVA) revealed significant effects (p < 0.01) of the genotype, the priming duration, and their interaction on traits such as the root length, dry mass, and root-to-shoot ratio. PCA identified the whole-plant dry mass, root dry mass, and root-to-shoot ratio as key contributors to performance. Pearson correlation showed a strong positive association (r = 1.0, p < 0.001) between the priming duration and seedling biomass, although the extended imbibition time may partially explain this trend. Hydropriming, particularly for 36 h, showed promise in promoting early growth, indicating that it is a favourable low-cost intervention. Field-level validation is recommended to assess the practical scalability under diverse environmental conditions.