Investigation of hormonal treatments in physiological alterations of Sistan Yaghooti grapes

Yaghooti grape is the earliest ripening grape in Iran and has advantages such as good taste and high heat and drought resistance; but it has highly cluster density. Physiological alterations of Yaghooti grape in three growth stages, as well as the amount of accumulation of some physiological substances, under the three hormones gibberellic acid, indole-3-acetic acid, and abscisic acid. Abscisic acid hormone had the most positive effect on total chlorophyll and carotenoid levels. The average amount of total chlorophyll was equal to (25.51), (18.76) and (26.16) mg/ml in the pre-flowering, flowering, and post-flowering stages, respectively. Under three hormones, the protein level is greatly reduced by 70%, Gibberellin treatment in the third stage of cluster development caused a 26% increase in carbohydrate level. The guaiacol peroxidase increased under indole acetic acid, but other hormonal treatments decreased the amount of this enzyme in Yaghooti grapes. The biggest reduction was related to gibberellin treatment with nearly 80% of the control sample in the first and second stage of cluster development and 55% in the third stage. The amount of ascorbate peroxidase enzyme was accompanied by an upward trend under influence of abscisic acid. Also, all three hormones almost caused a decrease in catalase enzyme activity in all three developmental stages. Indole acetic acid increased the activity of polyphenol oxidase enzyme during stages. Gibberellin, apart from slightly increasing the activity of ascorbate peroxidase enzyme during flowering, strongly reduced the activity of three other enzymes during all stages.