Melatonin Decreases Negative Effects of Combined Drought and High Temperature Stresses through Enhanced Antioxidant Defense System in Tomato Leaves

In tomato (Lycopersicon esculentum L.), the effects of combined drought (D) and high temperature (HT) stress during flowering stage had not been studied in detail. Therefore, this study was conducted with an objective quantifying foliar spray melatonin under individual HT stress. At stage, D imposed through withholding irrigation, while exposing plants to ambient (AT) along increase +5 °C. Under + HT, were first subjected followed by a 5 °C AT. The duration or ten days. 80% available soil moisture, 100 µM sprayed on D, treated plants. Among stresses, increased thylakoid membrane damage decreased photosynthetic rate fruit yield more than Foliar produced [D: 31%, HT: 26%, 18%] antioxidant enzyme, viz., superoxide dismutase, catalase, peroxidase, ascorbate glutathione reductase, activity over stress-control 24%, 22%, 19%] 32%, 23%, 16%] Hence, it is evident that melatonin-sprayed may be associated defense system. Melatonin as novel biostimulator has great potential scavenging free radicals activity, which shields from therefore helps mitigation.