Effect of Humic Acid on Some Physical and Chemical Characteristics of Pomegranate (Punica granatum cv. Ardestani)

In order to evaluate the effect of foliar spray of humic acid on the yield and quality characteristics of pomegranate fruit, an experiment was carried out using a randomized complete block design with four replicates in Mahvalat city during 2014 and 2015. Foliar sprays of humic acid were carried out at four concentrations (0 (control treatment), 1000, 2000 and 3000 mg/L-1) at two stages, full bloom and one month after full bloom. Results obtained showed that humic acid sprays had significant effects on fruit yield, number of fruits per tree, fruit weight and fruit size. The highest yield and number of fruits per tree were obtained with the concentration of 3000mg/L-1 humic acid, whereas the heaviest and largest fruits were obtained with the concentration of 2000mg/L-1. Furthermore, humic acid sprays led to increases in TSS, pH, total anthocyanin and total carbohydrate and decreases in TA, in comparison with the control treatment. Foliar applications of humic acid had no effects on the juice antioxidant activity and total phenols. Application of humic acid increased the leaf concentration of N, K and Zn and decreased the leaf concentration of P, whereas it had no significant effect on the leaf Ca and Fe concentrations. Generally speaking, the results obtained showed that foliar sprays of humic acid led to increases in fruit yield through increases in the number of fruit per tree, fruit size and fruit weight, and also it improved the quality parameters of pomegranate fruit.