Growth and dry matter partitioning of Pinot Noir (Vitis vinifera L.) in relation to leaf area and crop load

Abstract

Treatments varying source:sink ratio (leaf number per vine in relation to crop load) on container-grown Pinot Noir grapevines produced differences in vine growth and dry matter accumulation and partitioning. Vines with (+) and those without (-) fruit were subject to a range of leaf removal treatments. All treatments retained leaves at nodes 1-4 from the shoot base and then had: 100% (control); 66%; 33%; or 0% leaves retained from node 5 to the apex of the shoot. Leaf removal was done as leaves appeared. Leaf removal reduced vine weight. The presence of crop and the number of leaves influenced nodes per shoot and dry weight of the shoots. Removal of leaves did not influence shoot length although uncropped vines were larger in all of the above categories. Removal of either leaves or crop had an impact on leaf number, area per vine, area per leaf and leaf dry weight. '+ crop' vines carried fewer, and smaller leaves then the '- crop' vines. Carbon partitioning between above ground vegetative organs and roots followed the same relationship, regardless of harvest date, crop status or defoliation treatment. The '- crop 33% leaf retained' vines compensated for leaf removal by increasing their leaf size and dry weight over the '66% leaf retained' and the control.