Seleniumin rice: biofortification, physiological aspects and tolerance to hydric stress

Abstract

Selenium (Se) is essential to humans and animals due to its antioxidant properties. Although not essential to plants, many studies show its beneficial effects. Despite being essential to humans, consumption by Brazilian population is low, especially considering the low-income classes. Thus, the increase of Se through agronomic biofortification in highly consumed foods, such as rice, is an alternative to mitigate the shortage of this element. Therefore, the objectives of this work, which was developed by means of two experiments, were to evaluate: a) content and accumulation of nutrients in rice plants with Se application; b) the performance of rice plants submitted to normal irrigation conditions and under water deficit, with the application of Se; c) photosynthesis, grain yield and antioxidant system of rice plants, with the application of Se; d) the content of Se in rice plants and grains. The results of the first experiment demonstrate that the application of Se increases the levels of the element in the plant, improves the antioxidant system, and decreases oxygen reactive species. However, it does not promote productivity gain. Foliar application is the most efficient method for enriching Se in rice grains. However, studies focused on the application of smaller doses are necessary, given that the contents found in the grains are above recommended levels. It is also necessary to investigate the residual effect of Se application by fertilizer in subsequent crops. The results of the second experiment indicated that the application of Se decreases the effects of water stress on rice plants by improving photosynthesis, water use efficiency and the antioxidant system, in addition to increasing grain content. Water stress reduces nutrient content of the plant, phytomass and grain production, and Se content in grains. However, further studies under field conditions must be conducted, since other abiotic factors may interfere in plants development.