Fruit composition and ripening of Pinot Noir (Vitis vinifera L.) in relation to leaf area

Fruit development from pea size to maturity was investigated in grape berries on fruit-bearing cuttings subjected to a range of leaf removal treatments. Pot-grown vines were trained as a single shoot, with four basal leaves retained. From this point four treatments were applied: 100% leaves retained (control); 66% leaves retained; 33% leaves retained; 0% leaves retained. Leaves were removed as they appeared. The fruit of all treatments passed through veraison, accumulated water, coloured and displayed the typical double sigmoid change in volume, but the onset of growth and colour development associated with ripening was delayed by up to 25 days when leaves were removed. Berry dry weight, sugar content and soluble solids were more affected by leaf removal than berry volume or fresh weight. Bunches from the 0% leaf retained treatment formed seed, but increased very little in dry weight or soluble solids during the course of sampling. This indicates that seed growth and development are independent of sugar accumulation in pericarp tissues.