Micronutrients and Planting Time Effects on Maize Growth, Fertility, and Yield-Related Traits Under Heat Stress Conditions

Abstract

The recent study pursued determining the ideal quantity of micronutrients and planting time to enhance maize (Zea mays L.) pollen fertility and production under heat-stress conditions. The study set up a maize experiment in a randomized complete block design (RCBD) with split-plot arrangement and three replications, carried out in the crop season 2020 at the Babylon Muradia Research Center, Iraq. The trials comprised two factors: first, planting times placed in main plots, i.e., June 25 (A1), July 10 (A2), and July 25 (A3), and the second included foliar applications of a composition of six microelements (iron, manganese, zinc, boron, copper, and molybdenum) with four concentrations, i.e., 0 (C0), 20 (C1), 30 (C2), and 40 (C3) g L -1 . The results indicated that maize planting at later dates, specifically between July 10 and 25, resulted in the maximum levels of moisture, pollen vitality, and fertility percentage, which led to an increase in yield components and grain output. The findings also demonstrated that foliar application of micronutrients effectively creates a conducive environment for developing pollen grains. The micronutrient concentration of 40 g L -1 gave the optimal moisture and vitality of the pollen grains, leading to the highest quantity of grains per row and, ultimately, maximizing the maize yield. The July 10 planting date proved the ideal time for seeding maize because it contributed to reducing temperatures' effects and increasing productivity. In addition, foliar application of micronutrients (40 g L -1 ) creates an optimal environment for pollen grains, improving grain composition and yield. With the pollen grain's better vitality, the favorable situation improves pollination and fertilization, eventually increasing the maize yield.