Effect of Foliar Application of Nitrogen, Iron and Zinc Before Flower Induction on the Yeld and Quality of Sweet Lime (Citrus limettioides Tan.) Fruits

This study was conducted to investigate the effects of nitrogen, iron and zinc on the fruit quantity and quality of the 6-years-old sweet lime trees budded on Mexican lime rootstock in the research orchard of Jahrom Islamic Azad University. For this purpose, nitrogen, zinc and iron elements (from sources urea, iron sulfate and zinc sulfate, respectively) were foliar sprayed at concentrations of 0, 3 and 5 g L-1, alone and in combination, before flower induction, in October 2017. The experimental design was factorial based on the randomized complete block design with 27 treatments and three replicates and one sweet lime tree per each replicate performed at two separate locations in the orchard named groups A and B (each group included 81 trees). Based on the results, different amounts of nitrogen, iron and zinc, individually and in combination, had significant effects on all quantitative and qualitative traits of sweet lime fruit atP≤0.05. The effect of location was significant only on the total acids, vitamin C and fruit juice percentage. The highest average fruit weight (228 g) and yield of a single tree (313 kg) was obtained from the combined application of N, Fe and Zn elements at the highest concentration (5 g L-1). The highest TSS and total acid (10.62% and 0.208 mg L-1, respectively) were observed by application of 5 g L-1 Fe without N and Zn, in addition the greatest vitamin C was recorded by application of combined treatment of 3 gL-1 N and Fe and 5 gL-1 Zn with 56.93 mg/100 ml fruit juice.