Effect of Shoot Number on the Leaf Area and Crop Weight Relationship of Young Sangiovese Grapevines

Abstract

Five-year-old Sangiovese grapevines were shoot-thinned in early spring to three levels: 12 shoots (12SH), 20 shoots (20SH), and 28 shoots (28SH) per vine. Primary and lateral leaf areas per shoot and per vine were determined by regression on measured shoot length. Yield was measured at harvest and pruning weight measured at dormant season pruning. Vines thinned to 12SH had longer and heavier shoots, more leaf area per shoot, and a greater percentage of leaf area as lateral leaves. Leaf area per vine and pruning weight per vine did not differ with shoot number. Data presented support the conclusion that increasing the bud number at pruning or increasing the shoot number during spring shoot thinning decreases the percentage lateral leaf area, decreases the leaf area to fruit weight ratio, and increases the Ravaz index.