Foliar application of magnesium and amino acids to off-season maize: a strategy to improve photosynthetic and antioxidant metabolism

Introduction: In Brazil, maize is commonly cultivated during the off-season (fall/winter), a period characterized by reduced rainfall that substantially limits crop productivity. Foliar application of nutrients and amino acids has emerged as a promising strategy to mitigate physiological damage caused by water deficit by enhancing plant tolerance to abiotic stress. However, the combined effects of magnesium (Mg) and amino acids (AA) on off-season maize have not yet been investigated. Methods: A field experiment was conducted to evaluate the effects of foliar applications of Mg and AA on the photosynthetic and antioxidant metabolism of off-season maize. Four treatments were evaluated: (I) control, (II) foliar application of Mg, (III) foliar application of AA, and (IV) combined foliar application of Mg and AA (Mg+AA). Leaf nutritional status, photosynthetic traits, antioxidant enzyme activity, and grain yield were assessed. Results: The combined Mg+AA treatment improved leaf nutritional status, photosynthetic performance, enzymatic activity, and antioxidant metabolism compared with the isolated applications of Mg or AA. Grain yield increased by approximately 15% under Mg+AA relative to the control, whereas isolated applications of AA and Mg increased yield by 10% and 5%, respectively. Discussion: The results demonstrate additive effects of Mg and AA on the photosynthetic and antioxidant metabolism of maize plants. The combined foliar application of Mg and AA effectively alleviated stress effects and enhanced grain yield, representing a promising strategy to improve the productivity of off-season maize under field conditions.