Using canopy management and plant growth regulators to enhance fruit maturity of Cabernet franc under Southern Oregon conditions

Abstract

Wine grapes have shown tremendous promise crop in Southern Oregon. The grape growers and winemakers have expressed their interest in more research on optimization of canopy management practices or introducing new technology to improve fruit quality and mitigate seasonal variation. The aim of this study was to assess the effect of canopy management practices (shoot and crop thinning) and plant growth regulators (PGR) on vine performance and fruit quality. The experiment had a split block design with three replicates. The experiment was a combination of five canopy treatments with three different foliar products applications. The canopy treatments were applied as main plots [(1 shoot/spur + 1 cluster/shoot; 1 shoot/spur + 2 clusters/shoot; 2 shoots/spur + 1 cluster/shoot ; 2 shoots/spur + 2 cluster/shoot; – control (no canopy management other than hedging)] and chemicals foliar application treatments as subplots (control- non sprayed; ABA (abscisic acid) solution 300 mg/L applied before veraison; ALA (5-aminolevulinic acid) foliar spray 300 mg/L; Brix mix (mix of various nutrients) three times during the growing season, beginning with one week before veraison. Overall, canopy management treatments had a greater effect on yield and fruit composition compared to PGR or foliar nutrients alone. However, there was a significant variation among the interactive effect of canopy management treatments and PGR. The synergistic effect of the variables studied was much greater on fruit quality compared to the individual treatments. ABA treatments had consistently smaller berries but there were not consistently associated with the highest Brix. Brix mix consistently improved the berry chemistry. The berry volume was not affected by any treatment, however the weight and chemical composition of berries were significant affected. Understanding the synergism effect of different cultural practices could improve fruit quality and uniformity and might alleviate the effect of seasonal variation.