External potassium mediates the response and tolerance to salt stress in peanut at the flowering and needling stages

Potassium (K) is an essential macronutrient that plays an important role in abiotic stress tolerance. A pot experiment was carried out to identify the potential role of potassium fertilizer in alleviating salt stress in peanut. The results showed that salt stress significantly decreased plant height, dry mass, photosynthetic pigments, the photosynthetic rate, and stomatal conductance, but increased the Na+/K+ ratio, total sugars, and the leaf salinity hazard coefficient in two peanut varieties. However, the application of potassium significantly alleviated the harmful effect of salt by improving the contents of photosynthetic pigments and enhancing K+/Na+ ratios and osmolytes in both varieties. In general, HY25 showed a superior osmoregulation ability compared to that of HY33 and was less dependent on K+ to maintain osmotic balance. Therefore, HY33 showed a better response to potassium application, and the treatment by 170 kg(K2O) ha-1 was found to be the most effective in alleviating the harmful effects of salt. In conclusion, potassium reduced the toxic effect of salt and significantly enhanced salt tolerance.