Berry Growth and Biochemical Characteristics of cv. Trakya Ilkeren (V-vinifera L.) as Influenced by Various Doses of Pre-Harvest Hydrogen Peroxide and Phenylalanine Applications

Abstract

Uneven grape ripening, leading to decreases economic valued of grapes is one of the main problems faced by grape growers in early table grape growing. In recent years, there has been increasing concern about improving of fruit quality in fruit crops. Among the various quality improvement methods, different types of foliar compounds are used for this purpose and hydrogen peroxide (H2O2) and phenylalanine (Phe) can be given as examples to some of these chemicals. This research was carried out during the 2015 growing season by using early ripening table grape cv. Trakya Ilkeren. In the study, it was assessed that how different doses of hydrogen peroxide (0, 10, 20 and 40mM) and phenylalanine (0, 1, 2 and 4mM) affected physical and biochemical properties of cv. Trakya Ilkeren. In terms of physical properties, doses of hydrogen peroxide and phenylalanine had only significant effects on grape firmness and cluster length. The best results were obtained from 4mM Phe application (6.76N) in grape firmness and were obtained from applications of 10, 20 and 40mM H2O2 (23.66, 23.86 and 23.99cm) and applications of 1, 2, and 4mM Phe (23.95, 24.46 and 24.88cm) in cluster length. However, most of biochemical properties were considerably affected by doses of hydrogen peroxide and phenylalanine except for juice pH and p-value. It was recorded that the highest total phenolic compounds contents varied from 3571.28 (10mM H2O2) to 3871.22mg GAE kg(-1) fw (40mM H2O2) compared to 0mM application (2591.48mg GAE kg(-1) fw). In terms of total anthocyanin content, the highest mean was recorded for 4mM Phe application (330.56mg GAE kg(-1) fw) than 0mM application (168.79mg GAE kg(-1) fw). As aresult, 4mM Phe application particularly improved the most of biochemical properties in cv. Trakya Ilkeren.