Growth of ‘Thompson Seedless’ Grapevines: I. Leaf Area Development and Dry Weight Distribution

Data were collected over 3 years to provide detailed information on growth and development of ‘Thompson Seedless’ grapevines used for raisin production. Leaf area and leaf, shoot, and cluster dry weights were measured throughout the growing season. Results were plotted against growing degree days (GDDs), using a minimum temperature threshold of 10°C, after budbreak. There was a linear increase in leaf area and vegetative dry matter from about 200 to 1000 GDDs after budbreak. Cluster dry weight increased linearly from 750 GDDs after budbreak until harvest. While shoot numbers per vine increased 70% from 1983 to 1985, there was not a similiar increase in the amount of dry matter per vine. Weight per unit leaf area (W_L) increased from ≈ 40 g·m^-2 early in the season to >65 g·m^-2 90 days after fruit harvest. Results indicate that vines in this vineyard maintained a constant growth pattern year after year when growth was plotted vs. growing degree days.