Influence of pre-harvest spraying of gibberellic and boric acids on the growth and fruit characteristics of pomegranate fruit cv. Shishe-Kab

Influence of foliar application of gibberellic acid and boric acid on fruit growth and characteristics of pomegranate cv. Shishe-Kab was carried out in the research orchard of Birjand University during 2017 and 2018 seasons. The experiment conducted in a randomized complete block design with six replications. Experimental treatments were control (spray with distilled water), gibberellic acid at 50 and 150 mg L-1 and boric acid at 200 and 600 mg L-1. Gibberellic acid and boric acid sprayed three times at one-month interval started from late May, to July during fruit growth and developmental stages. At mid-October fully mature fruits were harvested and fruit quality and quantity were assessed in the laboratory of Department of Horticultural Science, University of Birjand. Results of this study indicated that foliar application of gibberellic acid and boric acid decreased chroma of pomegranate peel in 2017 and 2018, while it increased hue of pomegranate peel. Foliar application of boric acid significantly increased length, volume, fresh weight, and juice content of pomegranate fruit. However, peel thickness and sunburned were significantly increased by application of gibberellic acid in both studied years. Total acidity was significantly increased by application of gibberellic acid in 2018 season. Leaves chlorophyll content increased by application of 150 mg L-1 gibberellic acid and 200 mg L-1 boric acid in both seasons. Application of 50 mg L-1 of gibberellic acid significantly increased total soluble solid of pomegranates in 2017 and 2018. This result showed that foliar application of gibberellic acid and boric acid had positive effects on quality and quantity properties of pomegranate fruits cv. Shishe-Kab cultivar and it may be used to improve fruit production. However, further studies need to determine the exact application time and concentration for practical application.