Investigation of the alternate bearing mechanism in the Siirt (Pistacia vera L.) at molecular and phytochemical levels

The genus Pistacia belongs to the Anacardiaceae family and includes 9 species and 5 subspecies. Pistachio production in the world is common in Iran, the US, Turkey, Syria, Italy and Greece, where the most production takes place between countries. Pistachio cultivation in our country is made in 56 cities. However, the Southeastern Anatolia Region meets 94 % of the production.Pistachio is edible, delicious, nutritionally high and economically important plant. Periodicity in pistachio and many plant varieties is seen as a major problem encountered in agrilture and causes loss of income for the producer Alternate bearing is the phenomenon by which trees bear an irregular crop year after year, usually heavy yields which are followed by light ones. Recently, the physiological aspects of periodicity have been studied. In this thesis, it is aimed to investigate the molecular and phytochemical parameters which may be effective on the mechanism of periodicity in Siirt varieties. For this purpose, leave, stem and fruit samples of Siirt cultivars (on and off year) were collected. Then, in these tissue samples, several phytochemical parameters such as organic phenolic acids, sugars, volatile fatty acids, nitrogen protein contents, plant nutrients, which are thought to be related to periodicity, were analyzed. As a result of the study, the expression levels of some genes that may be related to the periodicity of the pistachio showed differences. In addition, most of the phytochemical parameters were different in on and off years. Keywords: Alternate bearing, geneexpression, Pistacia vera L., phytochemicals