Effects of Partial Rootzone Drying on the Growth of Vitis vinifera cv. Malvasia Grafted on Different Rootstocks

To lay a biological foundation for rootstocks and alternate irrigation (AI) popularization, the effects of partial rootzone drying (PRD) on the growth of the grapevine Malvasia grafted on different rootstocks were investigated. Biological effects of 112 divided root irrigation on three combinations, i.e., Malvasia/420A, Malvasia/3309C, and Malvasidl 10R, were studied by wood-boxed plants. All the plants were separated into three groups for different irrigation strategies. Mass growth of new root in alternate-irrigated plants was remarkably promoted by about 7.8-22.2% higher than the well- watered ones. However, new shoot growth, especially the internode was reduced by alternate irrigation. The average root-shoot ratio of all the three combinations was increased from 1.1 to 1.46. New root growth and internode length were decreased by fixed partial rootzone irrigation (FI) at different amount, M/3309C at 37.9 and 36.9%, M/llOR at 18.4 and 22.5%, respectively. Total biomass of all the three combinations under FI decreased at the rate of 19.2-34.3% compared with well-watered ones. Water stress adaptation of grapevine mainly depends on rootstock. llOR is more efficient than 3309C and 420A in water stress adaptation. PRD-A1 benefited root growth, thus improved the drought-resistant ability of grapevine.