Effect of Zinc and Iron Foliar Application on Corn Yield and Redistribution of Photosynthetic Materials in Water Stress Conditions

In order to evaluate the effect of iron and zinc on maize grain yield and the contribution of current photosynthesis and photosynthate redistribution under water stress conditions, this study was conducted in two seasons (2018-2020) in research farm at northwest of Ahvaz. The experiment was conducted in split split-plot design with randomized complete block design with three replications. Main plots consisted of water stress at three levels including complete irrigation, cut-off irrigation at vegetative growth stage (CI-VGS), and cut-off irrigation at early seed stage (CI-ESS). Sub-plots consisted of foliar application of zinc sulfate with three concentrations (0, 0.5 %, and 1 %) and sub sub-plots received foliar application of iron sulfate at three concentrations (0, 0.3 % and 0.6 %). The results showed that cut-off irrigation at CI-ESS decreased grain yield, biological yield, current photosynthesis rate, and current photosynthetic contribution, significantly (p<1%). But the redistribution of storage materials was the highest in this treatment. Also, 1000-grain weight in the CI-ESS was 26.9% lower than that of complete irrigation. The highest biological yield and current photosynthesis contribution were obtained by leaf foliar application of iron sulfate. Foliar application of zinc sulfate with 1% concentrations in CI-VGS resulted in significant increase in grain yield of 33.7%, a 7.6% share of current photosynthesis and a decrease in the redistribution of storage materials. The highest grain yields (7062 and 6735 kg. ha-1) and current photosynthesis rate (536.6 g.m-2) were obtained in the foliar application of 1% ZnSO4 and 0.6% iron sulfate. In general, water stress reduced the contribution of current photosynthesis and, consequently, decreased grain yield of maize cv.704 hybrid, which could be compensated by foliar application of 1% zinc sulfate and 0.6% iron sulfate.