Absorption Kinetics and Efflux of Chloride and Sodium in the Roots of Four Grape Genotypes (Vitis L.) Differing in Salt Tolerance

Abstract

Grapevine is classified as a moderately sensitive plant to salinity. In this study, two sensitive (GhezelUzum and Shirazi) and two tolerant (H6 and Gharashani) grape genotypes, based on screening experiments under salinity, were selected. Hydroponically grown plants were treated with different concentrations of NaCl. Cl− and Na+ contents were significantly increased in different plant organs of all the genotypes. Under salinity, the roots of the tolerant genotypes accumulated higher Cl− content, compared to the sensitive ones. Cl− content in the shoots of sensitive genotypes was threefold higher than the tolerant ones. The absorption kinetics of Cl− and Na+ under salinity was fitted to the Michaelis–Menten equation. Cl− uptake rate in roots of sensitive genotypes was 2.84 times higher than the tolerant ones. And, Na+ uptake ratio was 1.98. There was significant positive correlation between Cl− and Na+ accumulation in all the genotypes under salinity, and the uptake ratio of Na+ was close to 4. Our studied sensitive genotypes showed a higher cytoplasmic and vacuolar Cl− and Na+ values, compared to the tolerant ones. The difference in salt tolerance among the genotypes can be related to different Cl− and Na+ influx, transport and efflux in the sensitive and tolerant genotypes.