| Abstrakt: |
Nitrogen plays an important role in the nutrition management of citrus trees and the production of uniform and quality products. Considering the role of nitrogen in increasing vegetative and reproductive growth, as well as the role of hormones in flower induction and fruit set, the effect of different levels of urea (0, 0.75%, 1.5%), and different times of its foliar application (Dec 22, Jan 5, Jan 20) on some leaf and bud physiological traits and floral dendsity were investigated in 'Kinnow' mandarin trees. The experiment was performed as a factorial in a randomized complete block design with three replications during two years. Leaf and node sampling was done at 1, 3 and 5 weeks after spraying to estimate ABA, IAA, and GA3 concentrations, flowering density and nitrogen concentration, . The results showed that after urea foliar application, the highest leaf and node nitrogen content was found in trees sprayed with 1.5% concentration of urea on Jan 5 in the off-year. The highest leaf and node GA3 content was derived from control trees in on-year. The highest amounts of ABA in leaves were reported at 0.75% urea concentration on January 20. The highest leaf and node IAA content was detected in plants sprayed with 1.5% concentration of urea in off-year. Also, different concentrations of urea increased the number of flowers, and the highest number was counted on the maximum urea concentration (1.5%). Depending on the urea concentration and the timing of its foliar application, the hormonal contents were different. The results showed that there is a significant difference between off- and on-years concerning auxin, abscisic acid and gibberellic acid in both leaf and node in 'kinnowa' mandarin trees. [ABSTRACT FROM AUTHOR] |
