The response of berry organic acids of four organically grown table grape cultivars to cane-girdling and cluster-berry thinning treatments were evaluated over two growing seasons. In addition pH, titratable acidity, soluble solids content and maturity index were also determined. Statistical analyses showed that individual organic acid content of the four grape cultivars were significantly affected by the treatments. Tartaric and malic acids of ‘Red Globe’ were mostly influenced by the cluster-berry thinning treatment. ‘Alphonse Lavalleé’ accumulated the highest tartaric acid and malic acid in both the girdled/thinned and the cluster-berry thinned vines, respectively. The control and girdled ‘Trakya Ilkeren’ vines had the most tartaric acid. Control vines also contained high malic acid amount. ‘Buca Razakısı’, on the other hand, had the most prominent tartaric and malic acid levels in the girdled/thinned and thinned vines, respectively. Quality parameters also showed significant differences among the cultivars in response to the treatments.

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