Foliar Application of Chelated Selenium Modulated the Chlorophyll Metabolism, Antioxidant Capacity, and Yield of Rice under Salt Stress

Exogenous application of chelated selenium (Se) has shown potential in alleviating salt stress in crops, yet its specific effects on the yield and rice remain elusive. This study investigated the impact of foliar application of different concentrations of chelated Se i.e., 0 (CK), 5, 10, and 15 mg L−1 denoted as T1, T2, and T3, respectively on morpho-physio-biochemical and yield attributes of two rice varieties i.e., Meixiangzhan 2 (MXZ2) and Liangxiangyou 868 (LXY868) under salt stress (0.1%). The results demonstrated that the Se application at 10 mg/L treatment exhibited the highest yield for both rice varieties among all treatments. Physiological analyses revealed that the 10 mg L−1 treatment elevated chlorophyll content and 5-aminolevulinic acid (ALA) levels during the grain-filling stage while inhibiting the activities of chlorophyll degradation enzymes i.e., chlorophyllase and pheophorbide an oxygenase). Moreover, Se application also modulated the net photosynthetic rates and leaf area index at grain filling stage and dry matter accumulation at maturity stage by 17.25 - 21.52%, 13.77 - 22.18%, and 14.95 - 19.01%, respectively. Furthermore, Se application at 10 mg L−1 treatment markedly improved antioxidant enzyme activities and reduced malondialdehyde (MDA) content, effectively mitigating salt stress-induced membrane damage. In conclusion, foliar application of Se at 10 mg L−1 proved to be the optimal dose for enhancing rice growth and yield under salt stress conditions.