Physiological Roles of Nickel on Antioxidant and Nitrogen Metabolism Increasing the Yield of Sugarcane Plants

Abstract

Sugarcane (Saccharum officinarum) is one of the main sources of sugar, energy renewable, and ethanol worldwide. Nitrogen (N) plays a plethora of structural and functional roles on sugarcane growth and development. Nickel (Ni) is a cofactor of urease enzyme, acting in N metabolism and antioxidant system in plants, potentially leading to enhanced use of absorbed N. This study aimed to evaluate Ni application on N metabolism, antioxidant system, and yield of two sugarcane cultivars (RB86 7515 RB96 6928). The experiment was composed by six Ni application rates (0; 0.25; 0.5; 1; 3; 9 mg kg−1) and two sugarcane cultivars. Application of Ni via soil increased photosynthetic pigments concentration, urease, and nitrate reductase activity, leading to an enhanced N metabolism in sugarcane plants. Fertilization with Ni also improved antioxidant system by increasing superoxide dismutase, ascorbate peroxidase, and catalase activity alleviating the stress caused by reactive oxygen species. The increased photosynthetic pigments and antioxidant systems led to a higher concentration of free amino acids and total sugars. The enhanced N metabolism and increased sugar accumulation were followed by an increase in leaf, root, stems dry weights, and tiller number. The application rate of 0.5 mg Ni kg−1 led to a higher yield in sugarcane cultivars. This study presents fundamental new insights regarding Ni effect on N metabolism and sugar concentration that can be helpful to increase the crop tolerance to abiotic stress, and this could potentially lead to increase sugarcane yield under field conditions.