Effect of Shoots and Clusters Density on Microclimatic Changes, Yield, and Fruit Quality of King Ruby Grapevines

T HE fruit quality of grapevines is a great importance for local consumption and export. Shoots and clusters thinning are substantial agricultural practices in grapevines to improve the berries quality. Herein, 10-years-old King Ruby grapevines were examined in two successive seasons. Four different levels of shoots number were applied (48, 42, 36, and 30, shoots/vine) with two different levels of clusters (30 and 24 clusters per vine). Results showed that the gradual decrease of shoots and clusters/vine improved vegetative growth parameters (shoot length and leaf surface area), total chlorophyll content, and microclimatic characteristics (light intensity, air temperature, and relative humidity); however, decreased yield/vine was observed. Consequently, enhanced chemical properties of berries (SSC, SSC/acid ratio total sugars, total anthocyanins, and total phenols) were obtained. In addition, an improved coefficient of wood ripening and total carbohydrates in canes was recorded. Moreover, the progressive increase in the number of shoots/vines in parallel with the decreased number of clusters/vine raised the cluster weight, cluster length, width, berry weight, length, and width. The thinning application of 30 shoots + 24 clusters per vine collectively achieved the significant highest values of vegetative growth, microclimatic parameters and berries quality, therefore, it could be recommended for application in King ruby vineyards under the Egyptian climatic.