Comparative efficacy of PEG and H2O2 priming in mitigating salt stress during germination and early seedling establishment of cowpea (Vigna unguiculata)

Cowpea ( Vigna unguiculata (L.) Walp.) is a vital legume crop commonly cultivated in marginal soils with low nutrient levels and limited water availability. However, salinity stress poses a significant threat to its germination and early seedling growth. Enhancing tolerance at these critical stages through seed priming offers a promising approach to utilize salt-affected lands. Therefore, this study investigated the potential of two exogenous osmopriming agents, Polyethylene Glycol (PEG) and Hydrogen Peroxide (H 2 O 2 ) alongside hydropriming (water) to enhance germination indices, seedling traits, and salinity tolerance in cowpea. The experiment was conducted under semi-controlled conditions using a Randomized Complete Block Design (RCBD) with three replications. Seeds of cowpea variety 'BARI Felon-2' were primed with distilled water (Hp), 20% PEG (P 20 ), and 10 mM H 2 O 2 (H 10 ) and seedlings were grown for 7 days under control (S 0 ) and 100 mM NaCl (S 100 ) conditions. Salt stress significantly ( P < 0.05) inhibited seedling emergence and establishment, reduced biomass accumulation, and triggered oxidative stress and Na + upregulation. Conversely, seed priming significantly ( P < 0.05) improved germination percentage, seed vigor index, total leaf area (TLA), seedling length, and chlorophyll content. While both osmopriming agents were effective, 20% PEG (P 20 ) exhibited the most significant stress mitigation, reducing malondialdehyde (MDA) content by 41% and increasing TLA from 0.07 cm 2 to 0.21 cm 2 (208% increase) compared to untreated stressed seedlings. In conclusion, osmopriming enhanced cowpea performance under salt stress by promoting early, synchronized emergence and chlorophyll synthesis. These physiological improvements mitigated oxidative damage and Na + toxicity, resulting in superior seedling growth and biomass production.