Chemical and Non-Chemical Thinning Treatments Influence Berry Growth and Composition of <Emphasis Type="Italic">Cv.</Emphasis> Shiraz Wine Grape (<Emphasis Type="Italic">V. vinifera</Emphasis> L.)

Yield management is important subject in modern grape growing and winter pruning and cluster thinning treatments were used for yield control. Standard cluster thinning is generally labor intensive and expensive method and grape growers try to new methods, which are alternative to cluster thinning for reducing berry set. The goal of the present research was to investigate the effects of chemical thinning treatments such as ethephon (ETH), gibberellic acid (GA₃), naphthalene acetic acid (NAA) and non-chemical thinning treatments such as early leaf removal (ELR) and standard cluster thinning (SCT) on decreasing grape yield and enhancing berry composition of cv. Shiraz. In this study, percentages of berry set of cv. Shiraz were decreased by both chemical and non-chemical thinning treatments compared to Control. The results from these two different thinning methods shown certainly significant differences in berry composition of cv. Shiraz. Eventually, the best results in improved quality characteristics of cv. Shiraz were obtained from ELR treatment and treatments of ELR, ETH, GA_3, NAA and SCT successively resulted in considerable enhancements in quality attributes of cv. Shiraz.