‘Chambourcin’ Grapevine Response to Crop Level and Canopy Shade at Bloom

Abstract

‘Chambourcin’ grapevines were thinned at bloom to leave 8, 16, or 24 clusters/m of row and half were covered with 80% shade cloth for five days. All treatments were repeated on the same vines for four years. Five days of shade at bloom had no effect on any parameter measured in 1999, 2000 and 2002. In 2001, yield was reduced by shade and the interaction between shade and crop level was significant. Flower number, berries per cluster and yield were increased by shade at 8 clusters/m, but decreased at higher crop levels. As clusters per meter of row increased, clusters per vine and yield increased linearly and the following decreased linearly: number of flowers, berries per cluster, cluster weight, juice soluble solids and pH. Fruit set and juice titratable acidity were not affected by any of the treatments. Results of this study confirm that ‘Chambourcin’ is very sensitive to crop level and crop level may need to be reduced to 8 clusters per meter of row or 9-14 t/ha to produce high quality wine under Midwest environmental conditions.