Role of rootstocks for salinity tolerance in grapevine: Changes in biomass, photosynthesis, abscisic acid and glycine betaine

Physiological response of four grape varieties, Cabernet Sauvignon, Sauvignon Blanc, Flame Seedless and Sharad Seedless grafted on rootstocks, Dogridge and 110-R was studied after 30 days of (100 and 250 mM) NaCl salinity stress. NaCl salinity increased Na⁺ and decreased K⁺ content significantly in the varieties raised on Dogridge rootstock, and in Sharad Seedless. Flame Seedless raised on 110-R, recorded high K⁺ and low Na⁺: K⁺ ratio under salinity stress. The leaf and stem dry mass were negatively influenced by the salinity treatment and Flame Seedless and Cabernet Sauvignon raised on 100-R, showed less reduction in mass under NaCl salinity. Root dry mass of Cabernet Sauvignon and Flame Seedless was higher at 100 mM but declined at 250 mM NaCl treatment, while those on 110-R rootstock contained higher root dry mass. The root: shoot dry mass ratio consistently increased under salinity, and the varieties raised on 110-R rootstock showed high root: shoot dry mass ratio. The leaf water potential (w), osmotic potential (ð), specific leaf weight, photosynthesis rate (Pₙ) and chlorophyll content were high in plants raised on 110-R rootstock, and in Flame Seedless variety at both the salinity levels. Abscisic acid (ABA) and glycine betaine (GB) contents were high in Cabernet Sauvignon and Flame Seedless raised on 110-R rootstock under NaCl salinity. Abscisic acid content with Na⁺/K⁺ ratio (R² = 0.811, p≤0.05) and GB content with leaf water potential (R² = 0.782, p≤0.05) showed high negative relationship due to the salinity. Thus, induction in ABA and GB accumulation under salinity in grafted plants was associated with the rootstock induced salinity tolerance in grapevines. The Flame Seedless vines raised on 110-R accumulated higher ABA and GB under salinity and witnessed low Na⁺ content and Na⁺: K⁺ ratio, and maintained high leaf water potential and osmotic potential and root: shoot dry mass ratio.