Impact of selenium, zinc and their interaction on key enzymes, grain yield, selenium, zinc concentrations, and seedling vigor of biofortified rice

Selenium (Se) is an essential micronutrient and important component of oxidase which protects cell membranes, eliminate the role of free radicals in the human body. Se is necessary for low Se rice genotypes and Se deficient areas. Zinc (Zn) is a micro-battalion that affects the growth, development, aging, drought resistance, disease resistance, and many other aspects for rice. The effects of Se and Zn fertilization on Se and Zn concentrations were evaluated including the response of superoxide dismutase (SOD), catalase (CAT) enzymes activity, and grain yield under single Se, Zn, and combined Se-Zn application using R725 rice variety in pot experiment with 8 treatments (0, Zn5, Zn10, Zn15, Se1, Zn5 + Se1, Zn10 + Se1, and Zn15 + Se1) mg/kg of soil and three replications. Moreover, germination% and seedling growth of resulted seeds from this experiment were evaluated for the agronomical benefit of farmers. The results revealed that Se and Zn had a cumulative effect on each other, but more Se increase was activated than Zn under the combined Se-Zn application. Zinc application had the small effect on Zn concentration in the different fractions but the positive effect on carotenoids and the yield (both applied alone and in combination with Se). Single Se application resulted in a positive effect on Zn accumulation in grain and husk with the high effectiveness of Se accumulation and loss during processing. Combined Se-Zn application had positive effect on carotenoids, CAT, grain yield, and total dry matter. Moreover, single Zn and combined Se-Zn application had a positive effect on germination% and seedling growth. Agronomic biofortification with combined Se-Zn supply provided both agronomic and nutritional benefits for rice in the current pot trail. However, as Se preferably accumulated in the edible part as compared to Zn, 1 mg Se/kg fertilization was unsafe for edible purposes according to the national standard of China (0.04–0.3 mg/kg) but could be recommended as medicine.