The Effect of Foliar Application of Calcium Nitrate, Calcium Chloride and Boric Acid on Intensity of Fruit Abscission of ‘Kaleh- Ghouchi’ Pistachio

Fruit abscission is one of the disorders in pistachio trees. Pistachio trees produce plenty of flowers, but only parts of the flowers are pollinated and set fruit. Environmental stresses and inadequate nutrition especially during flowering time have increased fruit abscission. This disorder by reducing the yield of pistachio led to economic loss. Yet, little research has been carried out on fruit abscission in pistachio. In order to evaluate the effects of foliar treatments with calcium nitrate (2 gr/lit), calcium chloride (2 gr/lit), boric acid (200 ppm) and their combination treatments were studied on fruit abscission of ‘Kaleh- Ghouchi’’ pistachio. Treatments were applied one week before and also two weeks after full bloom. The experiment was conducted by using a split plot base on a completely randomized block design (CRBD) with 5 replicates per treatment on 13-year-old ‘Kaleh - Ghouchi’ pistachio trees grafted on Badami- Riz rootstock. The selected trees were “on” years. Two weeks after full bloom, in each cluster, the number of fruits were counted and fruit abscission was studied in three different stages at intervals of 15 days and in each stage of the test, the disorder fruits were dissected and embryo condition was studied by binocular too. The results showed that at all of the stages, dissected fruit have the embryo and no observed blanking fruit. Also, the results showed that all applied treatments in all three stages of evaluation decrease the fruit abscission as compared to control and Just boric acid treatment in the third stage of evaluation as compared to control have no superiority. While there were no significant differences between other treatments. In relation to the effect of treatments on the absorption of elements, results showed that the concentrations of calcium, boron, and nitrogen were different in treated and control trees. Treated trees with calcium nitrate + boric acid and calcium nitrate were absorbed the highest amount of calcium. Also treated trees with calcium nitrate + boric acid and boric acid, was absorbed the highest amount of boron. While treated trees with calcium nitrate + boric acid and calcium nitrate, was absorbed the highest amount of nitrogen. In this experiment, calcium nitrate + boric acid treatment was more effective than other treatments in improving yield traits.