REDUCTION IN JUNE DROP, A WAY TO REDUCE LOSSES OF SATSUMA MANDARIN (CITRUS UNSHIU)

Abstract

Citrus is one of the most important horticultural crops in Iran with area and annual production placing Iran as the 10th country in world citrus production. In spite of suitable climate, high crop losses, before and after harvest, cause reduction citrus average yield in Iran. Abscission of flower, fruitlet and fruit, is one reason of these problem. To evaluate the possibility of reducing June drop in Satsuma mandarin, an experiment was conducted in randomized complete block design with 8 treatments include: 1. control; 2. urea (1%); 3. urea + 2,4-D (15 mg/L); 4. urea +GA3 (15 mg/L); 5. urea + sucrose (1%); 6. urea + zinc sulfate (0.5%); 7. urea + zinc sulfate + 2,4-D and 8. urea + zinc sulfate + GA3 and 4 replications. Treatments were applied before starting June drop in 20 May 2006. After spraying until the end of June drop, number of abscised fruitlets was counted. Then percent of fruitlet abscission was determined in each treatment. Results showed that treatments 3, 5 and 8, reduced abscission significantly compare to the control. Treatment 8 reduced abscission and increased yield about 58 and 57% respectively. Also abscission and yield in treatment 8 were significantly better compared to all other treatments. However, average fruit weight and diameter in this treatment showed a significant reduction compare to the control. Treatments 3 and 5 had about 19.5% abscission reduction, 17 and 13% yield improvement, respectively, and didn’t have any significant difference in fruit weight and diameter compared to the control and therefore were the two efficient treatments in this experiment.