Long-term Response of Grapevines to Salinity: Osmotic Effects and Ion Toxicity

Growth, mortality, transpiration, and ion accumulation were evaluated in grapevines (Vitis vinifera L. cv. Sugraone) under variable conditions of salinity to evaluate whether mortality is a consequence of the processes causing growth and transpiration loss or whether it is an independent process coupled with ion toxicity. Six irrigation water salinity levels (electrical conductivity of irrigation water from 0.5 to 12 dS m−1 chlorine concentration from 3.8 to 149 mM) were applied in a one-year lysimeter study and four salinity levels (1.8 to 9.0 dS m−1; 10 to 75 mM chlorine) were applied for five years in vineyard conditions. In the lysimeter experiment, salinity-reduced transpiration was measured as early as 30 days after budburst, and biomass production and evapotranspiration were found to be linearly related. In both the lysimeter and field trials, mortality was dynamically associated with salinity level and time and corresponded to extreme accumulation of sodium and chlorine in shoots. Grapevine response to salinity involved two mechanisms: (1) a reduction in transpiration and growth, which began as soon as salinity was experienced; and (2) vine mortality, which was correlated with salinity level, a sharp increase in sodium and chlorine content of leaves, and time. At lower salinities, the onset of mortality occurred later and death rates increased as the duration of exposure to salinity increased.