The Influence of Rootstock on Leaf Water Potential, Yield, and Berry Composition of Ruby Seedless Grapevines

Abstract

An experiment was conducted to determine the effect of eight different rootstocks [99 Richter (99R), 110 Richter (110R), Rupestris du Lot (du Lot), 140 Ruggeri (140Ru), SO4, 41B, 101-14, and 1103 Paulsen (1103P)] on the productivity of non-irrigated Ruby Seedless grapevines grown in Morocco. Measurements taken over a three-year period included fruit growth and maturity indices, yield, and pruning weights. Leaf water potential (ψ_L) was measured at various times during the second year of the study. Results indicated that midday ψ_L declined throughout the season for all rootstocks, averaging -0.9 MPa at fruitset and -1.3 MPa at fruit maturity. The diurnal time course of ψ_L averaged across all rootstocks was approximately -0.4 MPa before sunrise, -1.2 MPa around solar noon, followed by a recovery to -0.6 MPa shortly after sunset. An analysis of seasonal, midday ψ_L indicated two extreme groups of rootstocks: du Lot and 110R had more negative leaf water potentials than 41B and 1103P. The difference between the two rootstocks with the greatest and the least negative average ψ_L, du Lot and 1103P, respectively, approached 0.2 MPa. Berry weight was greatest for vines on SO4, 99R, and 41B, and lowest for 101-14 and du Lot. At maturity, the lowest fruit soluble solids concentration was obtained on 99R and 41B while the lowest fruit coloration was obtained on 110R, du Lot, 140Ru, and 41B rootstocks. These results demonstrated that rootstock had a significant effect on Ruby Seedless fruit characteristics under non-irrigated conditions.