NaCl Enhance the Growth of Swiss Chard (Beta vulgaris L.) Leaves Under Potassium-Deficient Conditions

Potassium (K+) deficiency significantly reduces crop yield and nutritional quality in many arable lands worldwide. As a non-essential element in plants, Na+ is effective in alleviating the toxic effects of salinity under low K+ concentrations. The objective of this study was to evaluate the role of NaCl in modifying the response of Swiss chard (Beta vulgaris L.) to K+ deficiency at high concentrations and the effects of K+ deficiency on shoot growth, mineral assimilation, lipid peroxidation, and antioxidant enzyme activities in the presence of gradually increasing NaCl concentrations. Forty-seven-day-old Swiss chard seedlings were treated by individual K+-deficient conditions and combined conditions of K+ deficiency and salinity for 9 days. The results showed that both the shoot fresh and dry weights of the Swiss chard seedlings were markedly reduced when grown in the solely K+-deficient conditions, but the addition of NaCl significantly ameliorated the K+ deficiency-induced reductions in the shoot growth. NaCl also significantly enhanced the total phosphorus and PO43- concentrations in the leaves. Moreover, NaCl addition to the K+-deficient plants protected the cell membrane integrity instead of damaging the cell membranes. NaCl addition to Swiss chard seedlings grown in K(+-)deficient conditions has the potential to minimize K+ deficiency-induced damage and maintain the growth of the plants to levels comparable with control conditions.