Interaction of Irrigation and Pruning Level on Growth and Yield of Shiraz Vines

Abstract

We examined the effect of irrigation (trickle irrigation three times a week replacing 0.6 of Class A pan evaporation) and no irrigation on the yield, pruning weight, shoot number, vigor, fruitfulness and bunch weight of <i>Vitis vinifera</i> cv Shiraz in the hot, arid climate of Griffith, N.S.W., for five years from 1973. Four pruning levels, 20, 40, 80 and 160 nodes, were imposed on the two treatments. Irrigation increased yields at 80 and 160 nodes per vine in all years due to increased berry weight, the maximum increase recorded being 266% at the 160 node level in 1977. Irrigation at 20 and 40 nodes had less effect and in most years did not increase yields. Yields of the irrigated vines increased as the pruning level increased but were limited by the number of shoots that developed to maturity and because the number of berries per bunch declined. Pruning level had no effect on yields of the nonirrigated vines, except that yield increased when the pruning level increased from 20 to 40 nodes in 1973 and 1974. Irrigation increased pruning weight, but pruning level had no effect on the pruning weight of the irrigated vines. The increase in vigor of the severely pruned vines compensated for the reduced number of shoots. The basis for a balanced pruning system is discussed.