Anatomical and physiological characteristics of Raphanus sativus L. submitted to different selenium sources and forms application

Abstract

Increasing food production along with the nutritional value of diets with micronutrients and vitamins (e.g., selenium) is a worldwide concern that can be overcome by many strategies, including agronomic biofortification. This study tested different application forms and sources of selenium (Se) on Raphanus sativus L, assessing for their effects on characteristics such as biomass accumulation and Se content, as well as parameters related to gas exchange and anatomical modifications. The treatments consisted of two sources of Se (sodium selenate and sodium selenite) and two forms of application (soil and foliar application). A control treatment without addition of Se was also included. The experiment was conducted in a completely randomized design with 5 replicates, arranged in a 2 × 2 + 1 factorial scheme. The sources and forms of application did not affect plant biomass accumulation. The application of Se as selenate, via soil, resulted in greater selenium content in the plant, as well as in higher values of photosynthetic rate and instantaneous carboxylation efficiency, when compared with the other treatments. All treatments with Se resulted in increasing stomatal conductance, transpiratory rate, instantaneous efficiency of water use and intrinsic efficiency of water use when compared with the control treatment. Regarding the anatomy of the plant, the values of total area of the vascular bundle, xylem area, and number of xylem cells per cross-scectional area in leaves were higher when selenate was applied in the leaves, whereas the opposite was observed following the foliar application of selenite. The number of xylem cells per cross sectional area in the root was higher in the absence of Se. Our findings showed that roots of radish can be biofortified with Se without causing harmful effects, with the application of sodium selenate, and with a greater accumulation of Se when this source is applied via soil.