Effect of seed priming on Bambara groundnut under salinity stress

Salinity is a major abiotic stressor limiting the productivity of legume crops, especially in arid and semi-arid regions. Bambara groundnut (Vigna subterranea L.), a climate-resilient legume, holds great promise for food and nutritional security but remains underutilized and poorly studied under saline conditions. This study investigated the impact of magnesium nitrate Mg(NO₃)₂ seed priming on the morphological, physiological, and biochemical responses of two Bambara groundnut genotypes (BGN-14 and BGN-25) under salinity stress. Seeds were primed with 0.03% Mg(NO₃)₂ and exposed to 200 mM NaCl, with treatments including "control", "primed", "salt-stressed", and "primed + salt" conditions. The results revealed that salinity significantly impaired plant growth, reduced relative water content (RWC), chlorophyll and carotenoid levels, and increased oxidative damage through superoxide radical accumulation and cell death. However, Mg(NO₃)₂ priming significantly enhanced growth parameters, photosynthetic pigment concentration, water retention, and antioxidant activity, particularly in the "primed + salt" treatment. Notably, BGN-14 exhibited greater photosynthetic resilience and root-level antioxidant activity, while BGN-25 showed superior water conservation and shoot-based antioxidant responses. The study highlights nitrate priming as a low-cost, effective strategy to mitigate salinity-induced damage in Bambara groundnut, with genotype-specific mechanisms contributing to stress tolerance. The results provide a foundation for integrating Mg(NO₃)₂ seed priming into salinity management strategies aimed at improving the growth performance and stress resilience of Bambara groundnut in salt-affected agroecosystems.