Timing of Shoot and Bunch Thinning Treatments Affect the Chemical Composition and Monoterpene Profile of V. vinifera L. Cv. Cabernet Sauvignon Wine Grape

Abstract

Shoot and bunch thinning treatments are frequently employed for enhancing bunch sunlight exposure and obtaining better grape composition in wine grape growing. Timings of these treatments have momentous impacts on yield and quality characteristics of grapes. In present study, influences of two different canopy management practices such as shoot thinning (ST) and bunch thinning (BT) and three different treatment terms such as grape setting period, grape pea-sized period and verasion period on chemical composition and monoterpene characteristics of cv. Cabernet Sauvignon were assessed in Tekirdag, Turkey in the course of 2013 growing season. Study results pointed out that shoot and bunch thinning treatments and their treatment terms had diverse effects on yield and chemical parameters in cv. Cabernet Sauvignon. Among the shoot and bunch thinning terms, verasion period and grape pea-sized period were particularly determined to be more effective than grape setting period for enhancing chemical composition and monoterpene content of cv. Cabernet Sauvignon. As a result, although all shoot and bunch thinning treatments performed at three different terms had favorable effects on examined parameters compared to control treatments, ST3 (shoot thinning at verasion period) and BT3 (bunch thinning at verasion period) treatments obviously increased total phenolic compounds content, total anthocyanin content, free volatile terpene content and potentially terpene content of cv. Cabernet Sauvignon.