The effect of foliar nutrition of potassium sulfate on morpho-physiological indices of grapevine under salinity stress

Potassium has a main effect on plants salinity tolerance through its effect on cells osmoregulation, and the maintenance of cell turgor. The objective of the present study was to investigate the effect of foliar nutrition of potassium sulfate (PS; 0 and 1.5%) on some morphometric and physiological traits of Bidaneh-Sefid grapevine under salinity condition of NaCl (0, 25, 50 and 100 Mm). This experiment was carried out factorially based on completely randomized design in a greenhouse condition. The result showed that salinity decreased plant height, leaves number, leaves area and re-growth, but foliar application of potassium mitigated the negative impacts of salinity on these morphometric indices. Also, application of 1.5% potassium resulted in the stability of photosynthetic pigments compared to non-treated plants under salinity stress. With increasing salinity, the amount of ion leakage increased until salinity of 100 mM without PS treatment and reached to its highest level (64.2%). While 1.5% PS treatment decreased leaf ion leakage significantly (P≤ 0.01) in treated vines in compared to other untreated plants. Unlike insoluble sugar, the content of soluble sugar and proline as two osmoregulant has shown an increasing trend in the response to salinity and the application of potassium and reached to highest in 100 Mm NaCl and 1.5% PS treatments. Also, the PS foliar application use of sulfate-potassium leaf with increasing potassium concentration and then cell Na+ /K+ adjusting, increased the leaf N, K, Mg and Ca concentration in compared to non- PS sprayed plants.