Grapevine Irrigation with Saline Water: Effect of Rootstocks on Quality and Yield of Cabernet Sauvignon

Abstract

ABSTRACT The effects of three irrigation salinity levels (1.8, 3.3, and 4.8 dS/m) on ion accumulation and relative turgidity of Cabernet Sauvignon (Vitis vinifea) grapes on ‘Rugerri’ and ‘Salt Creek’ rootstocks were studied in order to introduce more saline water in the Negev Desert of Israel. Leaf samples were taken four times during the summer of 1997 and analyzed for total diffusible ions, which included sodium (Na), calcium (Ca), potassium (K), and magnesium (Mg), and for soluble ions, which included zinc (Zn) and manganese (Mn). Quality and quantity of yield were also measured. The lowest relative turgidity, 0.8, was measured at ECi (electrical conductivity of irrigation water) 4.8 dS/m, which decreased with time to 0.75 for all treatments. The Na/K ratio indicated relative sodium accumulation. It increased fast with time from about 0.1 to 1.4 under high salinity and more slowly, from 0.1 to 0.5, under the low-salinity treatment. Average yield of fresh berries under all treatments (except one) ranged between 8.0 and 8.5 kg/vine under the respective saline and fresh-water irrigation. This difference was not significant, but in view of the first-year experiment this result should be regarded as provisional. The juice quality criteria, as determined by the production of total soluble solids (TSS) pH2, improved from 321 to 288, indicating low acidity under the saline treatment and higher acidity under the non-saline treatment. The ratio of TSS/acidity, which changed slightly from 34 to 32, also indicated a moderate reduction in acidity under saline conditions, especially under the ‘Ruggeri’ rootstock. Thus, it was concluded that (a) by the use of saline water the quality of the berries may be improved, (b) ‘Ruggeri’ rootstock was less affected than ‘Salt Creek’ by salinity in both quantity and quality of yield, and (c) relative sodium (Na) content in the lamina and the petiole increased with time during the growth period while relative turgidity declined, indicating a possible accumulation of toxic ions over time.