Salinity Tolerance of Rice Genotypes: Response to Physiological Parameters and Seed Germination

Soil salinity is a major abiotic stress that limits rice production, with severity varying among genotypes. It disrupts key physiological processes, particularly water uptake and membrane integrity. This study evaluated six rice genotypes to (i) determine the critical salinity threshold for seed germination and (ii) investigate the physiological mechanisms underlying genotypic variation. Seeds were exposed to saline solutions of up to 32 dS m-1 under controlled conditions, and germination was recorded at 2, 5, 10, and 14 days after stress imposition. Additional assays at 0, 12, 18, and 24 dS m-1 for 1, 3, and 5 days assessed water uptake, electrolyte leakage, and malondialdehyde (MDA) accumulation. The critical threshold for germination was consistent across genotypes (26.01-28.53 dS m-1), except for Nona Bokra, which was more sensitive (20.5 dS m-1). Salinity reduced seed water uptake and promoted membrane degradation, as evidenced by increased electrolyte leakage and MDA accumulation, with severity proportional to stress duration.