Beneficial effects of potassium on growth, water relations, mineral accumulation and oxidative damage of Beta vulgaris in sodic-alkaline condition

Abstract

Potassium (K+) plays a vital role for plant growth and therefore the amount of K+ seems to be a key of plant development. Therefore, this study investigated whether the sodic-alkalinity tolerance of Swiss chard (Beta vulgaris L. subsp. cicla) could be increased, via greater water uptake, higher concentrations of mineral elements and higher antioxidant enzyme activities in sodic-alkaline stress conditions with K+ supplementation. Forty seven day old uniform seedlings were pre-treated in hydroponic medium with or without K+ for 7 days, and then treated in non-alkaline or alkaline conditions for 9 days. The absence of K+ somewhat intensified the effect of alkalinity on reducing the growth of Swiss chard, the total dry weight (DW) was reduced by 34% in plants treated in sodic-alkaline conditions without K+ when compared with plants with K+. Relative water content (RWC) of leaves was increased by 10% by K+ supplementation in sodic-alkaline conditions. Additionally, the osmotic adjustment was retorted; the contents of K+, Cl-, BO3-, Fe3+ and Mn2+, and the activities of catalase, guaiacol peroxidase, and glutathione reductase were increased. On other hand, K+ supplementation in sodic-alkaline conditions helped to maintain guaiacol peroxidase activity similar to that of control plants, and reduced malondialdehyde content when compared with plants treated in sodic-alkaline conditions without K+. In conclusion, the K+ supplementation resulted in favorable changes in plants with higher micronutrient contents and a reduction of oxidative damage induced by sodic-alkalinity in Swiss chard.