بررسي ريزش قبل از برداشت و ارتباط آن با ميزان اكسين در ناحيه ريزش ميوه پرتقال ايتاليايي CITRUS SINENSIS CV. ITALIAN

Investigation of pre harvest drop and its relation with auxin content in the abscission zone of Italian orange fruit (Citrus sinensis cv.Ttalian)

Citrus with annual production of more than 3.9 million tones constitutes first place among horticultural crops in Iran and sixth place in the world annual citrus production. Preharvest fruit abscission in some of citrus cultivars such as ʹItalianʹ cultivar is the main production problem that leads to the reduction of yield and reduce income with the loss of treeʹs resources. Regarding to average yield of Italian orange in the Baharestan orchard of Sari in the "on year", annually about 7.5 tons of yield per hectare abscise and destroy during pre harvest. To evaluate the possibility of abscission reduction in this cultivar, a randomized complete block design (RCBD) was performed with 7 treatments. Treatments were: I) control 2) 2,4-0 3) 2,4-0 and urea 4) 2,4-0 and zinc sulfate 5) 2,4D and sucrose 6) 2,4-0 and GA37) GA3and urea with 4 replications. In the third week ofNovember, treatments were applied, then fruits drop were counted in the week interval and finally the percentage of fiuit drop in all applied treatments were calculated. Calyx of harvested fiuits was collected and auxin content in the abscission zone was determined. Results showed that fruit drop in all applied treatments except treatment seven were reduced significantly compared with control. The highest treatments effect was observed with treatment 2 and 5 with 64 and 65 percent reduction of fruit drop, respectively. Average of abscission reduction in treatments except 7 was 60 percent compare with control. Sixty percent reduction in abscission is about 4.5 tons increase in the yield per hectare. Auxin content of abscission zone in all treatments showed that applied treatments caused increase of auxin content in the calyx and treatments 2, 3, 4 and 5 was significantly different compare with control. We conclude that the increase of auxin content in the abscission zone is the possibility of the reduction in fruit drop. So, according to the obtained results application of 2, 4-0 was an effective and economical way to reduce citrus pre harvest fruit drop.