INFLUENCE OF CROP LOAD ON FRUIT COMPOSITION USING PINOT NOIR GRAPES

Influence of Crop Load on Fruit Composition Using Pinot Noir Grapes Patrick G. Phelan November 2009 The two seasons for this trial were conducted in 2002 and 2003 at Bien Nacido Vineyard in Santa Maria, California. The trial consisted of pinot noir wine grapes clone 2a, grown on 101-14 rootstock. There were eight treatments with a control consisting of 25 vines per treatment, and 50 vines for the control. The primary objective of this research experiment was to conduct different vine balance procedures and compare them to the amount of wine phenolics. The vines were altered with two procedures. First was crop yield; fruit thinning altered the treatments by providing four different crop loads and a control. The treatment levels were signified as one ton, two ton, three ton, four ton, and control. The second procedure was timing of fruit thinning. Four different crop loads were split in half giving rise to eight treatments and a control. With four of the treatments the fruit was dropped post-bloom, and the other four treatments were dropped at seventy five percent veraison. Equal amounts of early and late thinning were combined and made into wine which gave four different crop load wines and a control wine. This process was done in 2002 and repeated in 2003. Additionally, other vine growth parameters were analyzed to determine the role that crop load and timing of thinning had in their development. Seven variables were analyzed from prunings, clusters, juice, and wine samples. They consisted of berry size, cluster weight, titratable acidity, pH, total soluble solids, phenolic profile (consisting of eleven components), and shoot weight. The results indicated that the following were statistically significant: (1) titratable acidity was significantly different between the 2002 and 2003 growing seasons, (2) total soluble solids showed a significant difference between the early fruit thinning versus the late thinning, (3) berry size in 2002 showed a statistically significant effect of drop date on the mean caliper size, (4) in 2002 the berry size also showed a statistically significant interaction between drop level and drop date, (5) berry size in 2003 showed a statistically significant effect of drop level on the mean caliper size, (6) in 2003 there is also a statistically significant effect of drop date on the mean caliper size, (7) again in 2003 there is a statistically significant interaction between drop level and drop date, (8) cluster weights in