Determination of mechanism of bud abscission in pistachio

In this study was carried 33 years of old P.vera cultivar, 'UZUN', which is grafted on P.vera rootstocks and shows absolute alternate bearing and normally grows in dry conditions that were planted in Dr. Ahmet Bilgen Research Station. Fruit buds samples, from three "On" year and three "Off" year trees in years 2014-2016 using were examined to determine abscission layer formation time and the begining of bud flower falling date light/fluorescent microscope and Scanning Electron Microscope (SEM) for histological analysis. On the other hand shoots, leaves, fruit bud, peduncles and fruits were sampled to research on the effects on pistachio bud abscission and alternate bearing polyamines, ACC synthase and macro- and micronutrient elements. As a result of this study, it is proved that abscission layer formation begins 'On' year 25 May and 'Off' year 14 June. It was determined that the amount of ACC and polyamine decreased when pistachio bud abscission and abscission layer formation time. It is thought that the N, P, K, Ca, P and F elements may have a key role in the annual fruit production and yield of pistachios. It has been proved that there is a relationship between alternate bearing and internal factors such as polyamines, ACC synthase and nutrient elements during different developmental stages in pistachio.