The effect of different concentrations of humic acid on morphological, phytochemical characteristics and antioxidant activity of Bidaneh Sefid grape

One of the valuable and rich sources of antioxidant compounds and vitamins is grape fruit. Nowadays, the production of high quality grapes with strong texture and high shelf life of fruits is very important. Therefore, the use of organic acids to improve the quality and quantity of crops and orchards is becoming more common. Humic acid, as an organic acid derived from humus and other natural sources, can work without damaging the environmental effects to enhance the quality of grapes. This study was conducted in a randomized complete block design with 4 replications. The experiment treatment consisted of four concentrations of humic acid (0, 0.5, 1 and 2 g L-1). Attributes such as weight, length and width of berry and grape panicle, as well as acidity, organic acids, soluble solids as well as some phytochemical traits such as total phenol and flavonoid, anthocyanin and antioxidant activity were evaluated by DPPH method. According to the results of analysis of variance, traits such as weight and width of berry and panicle, total phenol and antioxidant activity, acidity and soluble solids at 1% probability level were statistically significant between treated and control samples. But traits such as total flavonoid content and anthocyanin content of samples had significantly different at 5% probability level. In general, most of the traits had the highest values in the 2 g L-1 humic acid treatment. The highest total phenol content and antioxidant activity were observed in 2 and 1 g L-1 humic acid treatments with 1.667 mg ml-1 juice and 33.84%, respectively. In general, the results showed that application of humic acid can be improved many of the physical and biochemical properties of grape fruit.