Impacts of Preharvest Sprays of Fulvic Acid on Qualitative and Antioxidant Properties of Sour Cherry cv. Gysy'

Fulvic acid, as a humic matter obtained from decomposition of organic residues without any environmental destructive effects, is used in the production of horticulturaland agricultural crops. Many beneficial effects are attributed to foliar application of fulvic acid (FA), such as, enhancing antioxidant capacity, improving uptake of nutrients, reducing leaching of fertilizer and stimulation of plant metabolism. Some authors have also reported that fulvic acid could play a major role in resisting oxidative stress by enhancing antioxidative activity and improving membrane stability. However, there is little information about the effects of fulvic acid on antioxidant and quality attribution in sour cherry fruits. Thus, the objective of the present studies was to determine the effect of foliar application of fulvic acid on important quality characteristics and antioxidant properties of ‘Gysy’ sour cherries.

In this study, the effect of fulvic acid foliar application at different concentrations (0, 0.5, 1.5 and 2.5 gL-1) on quality and antioxidant properties of sour cherry friut was carried out in the completely randomized block design with three replications. Foliar spray was performed in the pit hardening stage(20 days after full bloom) and onset of ripening (46 days after full bloom) onto the leaves and fruits until runo using a mechanical mist sprayer, and Tween 20 (0.04% v/v) was used as a surfactant. Fruit were harvested at commercial ripening stage, and transferred to the laboratory on the same day, and finally the qualitative and antioxidant characteristics were assessed.

The results showed that fulvic acid significantly increased content of total soluble solids, firmness, vitamin C, anthocyanin, total phenolics and antioxidant capacity. Fulvic acid treatment showed less acidity compared with the control. While, mean fresh and dry fruit weight, length and diameter of fruit, titratable acidity (TA) and total flavonoid content were not affected by fulvic acid treatment (P<0.05). The experiment conducted here indicated that a preharvest application of fulvic acid improved nutritional quality and antioxidant potential of sour cherry fruits. The increased contents of phenolics, anthocyanins and ascorbic acid content, resulted in enhanced total antioxidant capacity. Generally, the best treatment for improvement of quality and antioxidant properties of sour cherry cv. Gysy was 2.5 gL-1treatment.