Evaluation of aqueous extracts of moringa leaf and flower applied through medium supplementation for reducing heat stress induced oxidative damage in maize

Heat stress induced oxidative damage is a major reason for reduced productivity in crop plants. This problem needs to be addressed by different ways and means but ecofriendly means, may be the application of aqueous extracts of different parts of plants. In this study, optimized concentration of 3% aqueous moringa fresh leaf extracts (MFLE), 10% aqueous moringa dry leaf extract (MDLE) and 15% moringa flower extract (MFE) were used for medium supplementation to find out effectiveness and possible mechanism involved in abolishing the heat-induced oxidative damage in selected heat tolerant and heat sensitive maize (Zea mays L.) hybrids. For the induction of heat stress, one set of ten day old plants was grown in plexiglass fitted canopies wherein the average temperature was 7-10°C higher than ambient while a control set was grown in the open net house. The plants were harvested after ten days of exposure to heat stress. Results revealed that heat stress induced the production of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), while reduced the biosynthesis of ascorbic acid, niacin, riboflavin, soluble phenolics and anthocyanins both in the shoot and root. Although application of all the extracts was beneficial in improving heat tolerance in both the maize hybrids, MDLE was the most effective followed by MFLE and MFE. The changes were observed in terms of reduction in the H₂O₂ and MDA generation, vitamins and phenolics synthesis. In conclusion, MDLE supplemented via medium was the most effective for improving heat tolerance in maize hybrids, although improvisation was substantially greater in maize hybrid SB-11. The extracts had a positive effect on the accumulation of vitamins and antioxidants with the production of ROS and minimizing the membrane peroxidation.