Seed Priming for Enhancing Germination and Early Seedling Vigour of Rice (Oryza sativa L.) under PEG-induced Osmotic Stress

Abstract

Drought is a significant abiotic stress that adversely affects rice productivity in Kerala by reducing water potential and disrupting physiological processes. This study was conducted at the Department of Seed Science and Technology, College of Agriculture, Vellanikkara, to evaluate the efficacy of seed priming in improving germination and early seedling vigour of the popular rice variety Uma under PEG-induced osmotic stress. The experiment followed a Completely Randomised Design (CRD) with three replications, testing 17 treatments including potassium nitrate (KNO3), silicon dioxide (SiO2), salicylic acid (SA), and moringa leaf extract (MLE) at varying concentrations. Osmotic stress was simulated using polyethylene glycol (PEG) 6000. Data were analysed by ANOVA followed by Duncan’s Multiple Range Test (DMRT) at the 5% level of significance. The results demonstrated that seed priming significantly mitigated the negative impacts of osmotic stress on germination and seedling vigour. For maximising total germination potential under stress, salicylic acid (SA) 6 mM was most effective (94.75%), followed by KNO3 2% (94.5%) compared with the control (92.91%). In terms of germination kinetics, MLE (dilutions 1:20 and 1:30) emerged as the superior treatment, consistently providing the highest speed of germination (43.90 and 43.37 versus 31.87 in the control) and coefficient velocity of germination (45.16 and 46.17 versus 31.89 in the control) under osmotic stress. While MLE promoted rapid initiation, chemical priming with KNO3 3% (SVI I: 2537; SVI II: 2096) provided better structural resilience, resulting in higher seedling vigour indices I and II under osmotic stress. The study concludes that seed priming, particularly with organic extracts such as MLE and chemical agents such as KNO3, SiO2 and SA, is a viable and effective strategy for improving the germination and early seedling establishment of rice under osmotic stress. Further field and physiological-level evaluation is required to demonstrate true drought resistance in Uma rice, as this work was restricted to laboratory-based germination and seedling-stage assessments under PEG-simulated osmotic stress.