Effect of Heat Stress Mitigators on Growth Performance of Wheat (Triticum aestivum L.) under Varying Sowing Windows

Abstract

Rising temperature adversely affects cereal production and threatens global food security. Wheat is highly vulnerable to heat stress, which reduces its growth, development and productivity. A field experiment was conducted during the rabi seasons of 2024–25 and 2025–26 at Bihar Agricultural University, Sabour, to evaluate the effect of heat stress mitigators on wheat growth under different sowing windows. The experiment was laid out in a split-plot design with three replications. Three sowing windows, namely timely sown, late sown and very late sown, were assigned to the main plots, while five foliar treatments, namely water spray, 2% potassium nitrate, melatonin at 100 µM, sodium nitroprusside at 100 µM and progesterone at 1 µM, were assigned to the subplots. Growth parameters were recorded at 30, 60 and 90 days after sowing and at harvest. Timely sowing produced the highest plant height, leaf area index and number of tillers m⁻², whereas very late sowing recorded the lowest values. Among the foliar treatments, 2% potassium nitrate produced the highest growth values and remained statistically comparable with sodium nitroprusside for most observations. At harvest, 2% potassium nitrate recorded a plant height of 98.80 cm, a leaf area index of 3.44 and 292.02 tillers m⁻². The corresponding values under water spray were 88.77 cm, 2.98 and 270.17 tillers m⁻². The interaction between sowing windows and heat stress mitigators was non-significant. The findings indicate that delayed sowing reduced wheat growth, while foliar application of potassium nitrate and sodium nitroprusside improved growth performance under the tested conditions.