Melatonin improved efficiency of 24-epibrassinolide to counter the collective stress of drought and salt through osmoprotectant and antioxidant system in pea plants

Abstract

Plant hormones and several small signalling molecules are known to provide tolerance against various abiotic stresses. The individual contributions of 24-Epibrassinolide (EBL) and Melatonin (ML) in enhancing plant tolerance to different abiotic stresses have been well-documented, but their combined effect in alleviating the impact of combined stress remains unexplored. In this study, joint effect of EBL and ML has been tested on growth, photosynthesis, biochemical traits and oxidative stress markers in Pisum sativum (pea) plants exposed to combination of drought and salt stress. The individual application of EBL and ML exhibited nearly similar responses to both stresses. However, when EBL and ML were applied together, significant changes in growth, photosynthetic traits, proline accumulation, and activities of various antioxidant enzymes were observed in pea plants exposed to the combined stress of drought and salt. Enhanced level of antioxidant enzymes and accumulation of proline indicates mitigation of excess ROS elicited by joint application of EBL and ML that provides tolerance against combined stress of drought and salt in pea plants. This study indicates that joint application EBL and ML is an operational approach for mitigation of combined stress of drought and salt in plants and could be exploited for sustainable agricultural practices on the stressed soils.