Effect of Shoot Girdling, Fruit Thinning, Urea, Zinc Sulfate and Sucrose Application on Inflorescence Bud Retention in Pistachio cv.  Ohadi'

To evaluate the effect of shoot girdling, fruit thinning, urea, sucrose and zinc on inflorescence bud retention in pistachio, an experiment comprised of 12 treatments including girdling, fruit thinning, application of urea (0.5%), and sucrose (3 and 5%) and their combination of the first two with urea plus zinc sulfate (0.05 and 0.1% of pure zinc) as well as a combination of the two with urea, in 3 replications and during 2 stages, was conducted in 2007 and 2008. The treatments were applied in two different stages of fruit growth and development namely: 1. Initiation of rapid growth of seed endosperm, and 2. Endosperm completion and initiation of rapid seed embryo growth. According to the results, all treatments decreased the inflorescence bud abscission while increasing inflorescence bud dry weight. The lowest inflorescence bud abscission and the highest bud dry weight were obtained through girdling. With the exception of 0.05% zinc and 3% sucrose, all the other treatments decreased inflorescence bud abscission significantly, also, significantly increased inflorescence bud dry weight. A study of the inflorescence bud retention at different times during the summer showed that the highest rate and quantity of bud abscission occured between 6th July and 6th August, while the role of the treatments was a reduction of flower bud abscission rate and quantity during this period. There was no significant difference observed among treatments in different stages of fruit growth and development.