Determining an Appropriate Fertilization Planning to Increase Qualitative and Quantitative Characteristics of Kiwifruit (Actinidia deliciosa L.) in Astaneh Ashrafieh, Gilan, Iran

The lack of balanced use of fertilizers is one of the reasons for the low yield and the low quality of kiwifruits in Gilan Province, Iran. In order to determine a suitable fertilization planning for kiwi orchards (Actinidia deliciosa L. cv. Hayward) in Astaneh Ashrafieh, an experiment was performed in 10 treatments with 3 replications based on a randomized complete block design with different amounts of fertilizers in different fertilizing methods. Treatments include different amounts of macro- and micronutrient fertilizers with foliar spraying of calcium, zinc, and potassium in different stages. In this study, the yield of each tree, the fruit firmness, sugar, pH, wet weight, percentage of dry matter, and the content of macronutrients (nitrogen, phosphorus, and potassium) and micronutrients (iron, zinc, and manganese) in the fruit were measured. The results showed that the treatment of 350 g urea, 500 g potassium sulfate, 500 g superphosphate, 80 g iron sulfate sprayed foliarly with 5 parts per thousand of zinc chelate and iron chelate, and foliar spraying with 0.5% of calcium during several stages for each tree has the highest effect on the yield of each tree, the fruit firmness, the fruit pH, and the percentage of the fruit dry matter, so such a yield of this treatment showed a difference of 7.9 kg with control.