Ameliorating Effect of GA3 Priming on Seed Germination and Seedling Growth of Rice Genotypes under Salinity Stress

Abstract

Aims: Salinity is a major abiotic stress limiting crop productivity, particularly in arid and semi-arid regions. Rice (Oryza sativa L.) is highly sensitive to salinity, especially during the germination stage. This study aimed to evaluate the effect of gibberellic acid (GA₃) seed priming on mitigating salinity stress and improving seed germination and early seedling growth in different rice genotypes. Study Design: The experiment followed a factorial block design under laboratory conditions, testing the interaction of four rice genotypes and varying salinity levels, with and without GA₃ priming. Place and Duration of Study: The lab experiment was conducted in department Plant physiology laboratory in GBPUAT Pantnagar over a period of four weeks. Methodology: Four rice genotypes Pant Basmati 1, Pant Basmati 2, Pant Sugandh 21, and CSR 36were evaluated under four NaCl concentrations (0, 50, 100, and 150 mM). Seeds were primed with 20 and 30 µM GA₃ and compared to untreated controls. Key germination and seedling parameters including germination percentage, shoot and root length, dry weight, seedling vigour index, and seedling tolerance index were measured and statistically analysed. Results: Increased salinity significantly reduced all measured parameters across genotypes. Pant Basmati 1 was most sensitive, while CSR 36 showed the highest tolerance. At 150 mM NaCl, germination occurred only in CSR 36. GA₃ priming significantly improved germination and seedling growth, particularly in sensitive genotypes. Pant Sugandh 21 and Pant Basmati 1 showed 30% and 23% increased germination, respectively, with GA₃ at high salinity. More than 15% improvement in shoot and root length was observed in all GA₃-treated genotypes at 100 and 150 mM NaCl. Conclusion: Seed priming with 30 µM GA₃ effectively mitigates salinity stress during rice germination, enhancing seedling growth and tolerance, especially in salt-sensitive cultivars. This approach holds promise for improving rice cultivation in salt-affected areas.