Sulfur Application Improves the Nutritional Quality of Maize by Regulating the Amino Acid Balance of Grains

Abstract

As a crucial staple crop in agricultural production, maize is extensively cultivated worldwide and plays a pivotal role in ensuring global food security. However, the significant deficiency of essential amino acids (EAA) and conditionally essential amino acids (CEAA), such as lysine (Lys), tryptophan (Trp), methionine (Met), and cysteine (Cys), leads to an imbalance of amino acids in the grain. This study investigates the regulatory mechanism of sulfur (S) application for regulating the amino acid balance of maize grains. The results demonstrate that S application has substantial effects on both the maize yield and nutritional quality. The S application resulted in an increase in maize yield by simultaneously enhancing the grain number per ear (GN) and 100-grain weight (GW), while S application elevated protein concentration through the augmentation of Cys concentration in maize grains. Furthermore, the Cys in grains optimizes the amino acid balance by regulating the ratio of other amino acids, thereby enhancing the nutritional quality of maize while ensuring a steady increase in protein concentration, simultaneously. Overall, the S application at 60–90 kg ha−1 synergistically improved both the yield and nutritional quality of maize, meeting the requirements for sustainable development in maize production. The findings offer a novel theoretical foundation and nutrient management approach for achieving high-yield and superior-quality maize production.