Effects of Exogenous Selenium in Different Concentrations and Forms on Selenium Accumulation and Growth of Spinach (Spinacia oleracea L.)

The objectives of this study were to determine if Selenium (Se) in the forms of Se (IV) and Se (VI) interact during uptake and assimilation by spinach plants (Spinacia oleracea L.), when they are applied together. That might affect selected physiological and morphological characteristics, and crop yield. Plants were foliar sprayed with different concentrations of Se as selenite and selenate, separately (each at the rate of 5, 10, 15 mg Se L-1), and simultaneously with selenite plus selenate (each at the rate of 5 mg Se L-1). Se accumulation in the spinach leaves was monitored, along with selected physiological and morphological characteristics. These foliar Se treatments had little or no effects on crop yield, content of photosynthetic pigments and UVA and UVB absorbing compounds, respiratory potential and plant biomass, and potential efficiency of photosystem II. This demonstrated the good conditions of the spinach plants under these foliar Se treatments. The spinach plants readily accumulated both forms of Se into the leaves. Direct comparison of their combined application (5+5 mg L-1) with their individual applications (10 mg L-1) showed that in the combined application, the plants accumulated Se more than in selenite alone treatment, but less Se than in the selenate alone treatment. Foliar spraying with all tested concentrations of selenite, selenate, or their combination ensured that spinach leaves were safe for use in human nutrition. According to our results, exogenous treatment with selenate in concentration of 15 mg L-1 was the most efficient treatment for production of Se enriched spinach.