Nowadays, the air temperature has risen as a consequence of climatic variability. The extremely high temperature causes heat stress and serious injuries to plant growth and development. Maize plants can operate most of its physiological process normally in the range of 0-400C. Heat stress reduces the uptake of water and nutrients which results in the reduction of plant growth, the source-sink relationships gets altered and it reduces the hormonal content which is being produced in roots and it affects the nutrient concentration of the plants which in-turn affect the productivity by causing injury to the plants.
To mitigate the heat stress, a field experiment was carried out in the high-temperature zone at Agricultural Research Station, Bhavanisagar, TNAU, India to reduce the heat stress-induced squandering to maize (Zea mays L.) plants with exogenous application of phytohormones during two consecutive years 2021 and 2022. The foliar spray treatments with phytohormones include salicylic acid 50 and 75 ppm, brassinolides 0.2 and 0.5 ppm, and sodium nitroprusside 50 and 75 µM along with control. The experiment was laid out in a Randomized Block Design (RBD) with four replicates. The result revealed that plants foliar sprayed with sodium nitroprusside 50 µM and salicylic acid 75 ppm at 40 and 47 days after sowing recorded the maximum plant height, early flowering, pollen viability, chlorophyll content and enzyme activities viz., catalase, peroxidase, and superoxide dismutase when compared to control. The yield parameters such as cob length, cob weight, and seed yield were significantly influenced by the foliar spraying treatments. The plants foliar sprayed with sodium nitroprusside 50 µM outperformed the other treatments during 2021 and 2022 by recording the highest seed yield by modulating the heat stress-induced losses to maize plants whereas the minimum yield was recorded in control.