Effects of canopy types on yield and berry quality of ‘Cabernet Sauvignon’

Abstract:【Objective】Raw grapes are the key to determine the quality of wine, and the grape maturityis mainly affected by many factors such as variety, temperature, light, moisture, and cultivation measures.Reasonable field cultivation management can increase the yield and quality of grapes. Environmentalindicators like canopy temperature and light intensity are the main factors affecting the growthand development of grapevine. A reasonable canopy can improve the light and temperature conditionsof grape microdomains and regulate the vegetative growth and reproduction of the vines. Vertical and Yshapedtrellising systems are most commonly used as a vine-growing practice in China. The cordon positionof vertical trellising system makes it easier for mechanical operation and vine burial for overwintering,while V-shaped canopy is more vigorous and has better berry quality. It has the characteristics ofhigh plant density and high yield, and is mostly used in the cultivation of fresh grapes. Compared withother cultivation techniques, changing the structure of foliage to regulate the microclimate of grape berriesand improving the yield and berry quality are the simplest and feasible technologies. The purposeof this study was to investigate the effects of vertical and V-shaped canopy on cluster micro-environment,yield and berry quality.【Methods】V-shaped and vertical trellis systems were applied in commercialvineyards of‘Cabernet Sauvignon’. The temperature and humidity around the cluster were collectedin 2018. The leaf photosynthetic indexes were measured from June to September 2018. The effectsof canopy types on photosynthesis, transpiration, the intercellular CO2 concentration and stomatal con ductance were determined at five stages during berry ripening. The external appearance, sugar, acidity,flavor compounds and seven anthocyanin-related genes were quantified at ripening stage.【Results】Theresults showed that the ratio of high temperature and the variations in humidity and temperature decreasedaround the cluster of V-shaped canopy, especially in July and August. Light environment wasimportant for the yield and quality of grape berries. V-shaped canopy resulted in significantly larger sizesof single cluster. The yield of V-shaped canopy was higher than that of vertical canopy by 20.57%.The soluble solids and reducing sugar contents with V-shaped canopy were significantly higher. The pHvalues of the two canopy types were similar. The berry color of V-shaped canopy was brighter and deeper.The contents of total flavanols and anthocyanins increased in grape skin with V-shaped system by9.16% and 12.92%, respectively. The gene expression related to anthocyanin metabolism pathway wasup-regulated with V-shaped canopy【. Conclusion】V-shaped canopy effectively regulated the micro-environmentaround clusters and could be applied to increase the yield of wine grape, and guarantee thequality of grape berries simultaneously.