Synergistic Effect of Selenium Addition and Water Stress on Melilotus officinalis L. Mineral Content

Abstract

The objective of this study was to examine the combined effects of selenium (Se) enrichment and water stress on the accumulation of available macro- and micronutrients in Melilotus officinalis L. aerial parts. Plants of M. officinalis were subjected to three levels of Se addition (0, 1 and 3 mg Se L^-1 water) and to two water treatments: a) full irrigation and b) limited irrigation (water stress). The above ground biomass (stems and leaves) was analyzed for Se, potassium (K), sodium (Na), magnesium (Mg), iron (Fe), copper (Cu), calcium (Ca), manganese (Mn) and zinc (Zn). Se addition differentially affected the K, Mg and Ca content of M. officinalis aerial parts, while it led to the reduction of the micronutrients Cu, Fe and Mn. Water stress resulted in the increase of K, Na, Mg, Ca and Cu, and to the decrease of the Fe, Zn and Mn content. An interaction between selenium addition and water treatment was more notable for Ca and Mg, which decreased under water stress at low Se level and for Zn and Cu, which increased under water stress at high Se level. According to our findings, Se-induced increased accumulation of some inorganic ions in the aerial parts of this species under water stress conditions could serve as a means to alleviate the adverse impact of water deficit on important metabolic processes, enhancing M. officinalis tolerance to water stress.