Boron toxicity in grapevine (Vitis vinifera L.) in conjunction with salinity and rootstock effects

Recycled wastewater in Israel is often saline and can contain high concentrations of boron (B). To evaluate the potential of recycled wastewater for irrigation, grapevines (Vitis vinifera L. 'Sugraone') were grown for 4 years in the Jordan Valley in perlite media-filled containers. Vines grafted on 'Ramsey' rootstock were irrigated at two salinity levels [electrical conductivity (EC) 1.3 or 2.7 dS m(-1)] combined with four concentrations of B (0.03, 0.12, 0.21 or 0.31 mM). The treatments were initiated on 6-month-old vines in 60 1 containers. After 2 years, the vines were transferred to 100 1 containers. Vine growth, yield and B uptake were measured and the results compared with vines grafted on 'Ruggeri' rootstock that received the same B treatments with low-salinity water. Exposure to increasing root-zone B led to severe visible symptoms of toxicity, increased B accumulation in the leaves, and eventually caused a decrease in woody vegetative production, but did not influence annual production, measured as pruning biomass and fruit yield. Rootstock had no influence on the response of grapevines to B. Higher salinity (EC = 2.7 dS m(-1)) reduced the levels of B accumulated in leaves and decreased the annual pruning biomass, but did not influence fruit production. The excess B found in recycled saline wastewater does not appear to be of practical commercial concern for the cultivation of early-ripening table grapes in the Jordan Valley.