The effect of humic acid application on growth characteristics and product quality and yield of pistachio

Today, in most pistachio farming areas, the reduction in the quantity and quality of irrigation water, followed by the reduction in the absorption of nutrients by the roots, has reduced the amount of pistachio fruit and its quality. The use of organic materials in sustainable agriculture, such as humic acid, causes the physical modification of the soil, including the increase of pores and water retention capacity and the reduction of evaporation from the soil surface. These substances increase the absorption of nutrients through the improvement of root growth and the formation of chelates of elements, and with the properties of stimulating growth, regulating plant growth hormones and increasing the tolerance of plants against plant stresses, it ultimately increases plant growth and Finally increasing the economic performance of pistachios. This research was carried out in the form of a randomized complete block design with 5 treatments including zero (control), 500, 1000, 1500, 2000 kg per hectare of humic acid produced by Shimi Golfaiz Khorasan Company in three replicates and for two years of cultivation on fertile trees of 35-year-old Kale Ghochi trees. Each plot included 5 trees and a total of 75 trees were tested. Based on the soil test, the lack of nutrients was determined and the required amount of chemical fertilizers (the same amount for all treatments) was used in a mixture with humic acid, and only chemical fertilizers were used in the control treatment. The results of analysis of variance and comparison of treatment averages based on composite analysis of two-year data indicated that the difference between treatments was statistically significant for most of the assessed traits. The fresh and dry weight of the tree showed an increase of 39% and 38%, respectively, in the treatment of 1500 kilos of humic acid compared to the control. The treatment of 500 kg/ha of humic acid had the lowest amount of blank (25% reduction compared to the control) and the highest percentage of non-splitting (48% compared to the control). The treatment of 1000 kg/ha of humic acid caused the highest branch growth with 21% compared to the control. The 1500 kilo humic acid treatment had the highest amounts of calcium (23%), iron (25%), zinc (22%), and manganese (24%) compared to the control. According to the results obtained from this research, the treatment of 1500 kgha-1 of humic increased the fresh and dry yield and the concentration of calcium and micro nutrients elements of iron, zinc and manganese and is introduced as the best treatment. Of course, it should be kept in mind that regardless of the type and concentration of humic acid used, the method of application, the physical and chemical conditions of the soil, the management of the farm are also effective in the results obtained.