Minimizing the Adverse Impact of Drought on Corn by Applying Foliar Potassium Humate Combined with Chitosan

Previous studies have demonstrated the impact of potassium humate (KH) and chitosan (CH) on ameliorating drought effects, but their combined applications in promoting these benefits are still unfound. Therefore, the current study aims to evaluate the efficacy of KH and CH on corn growth, yield, nutrient contents, and water productivity under full and limited irrigation conditions. Under the drip irrigation system, a split-plot experiment was performed with three replications in the second week of February in the seasons of 2021 and 2022. The main plot was equipped with a valve and a flow emitter to control the amount of the targeted irrigation levels (full irrigation and limited irrigation from the development stage onwards), as well as four foliar applications in the subplot (0, CH 500 mg l−1, KH 3000 mg l−1, and CH 500 mg l−1 + KH 3000 mg l−1). It was found that separate foliar applications of KH or combined foliar applications of KH + CH had a significant impact on the most examined traits. However, compared to the control, adopting limited irrigation and applying combined applications thereof have significantly increased iron, zinc, manganese, oil, protein, yield, and water productivity. In addition, this combination decreased proline, and the maximum reduction was observed for the combined application with adopting full irrigation. In arid regions, the researcher recommends treating stressed plants with combined foliar applications of KH + CH, which could help plants overcome the negative effects of drought and attain the highest yield and water productivity.