MORPHOLOGICAL-POMOLOGICAL CHARACTERISTICS AND ECOLOGICAL REQUIREMENTS OF PISTACHIO (Pistacia vera L.)

Pistachio ( Pistacia vera L.) is a perennial, deciduous, generally single-trunk and dioic plant that can grow between 3-10m depending on the rootstock type with a habitus like an open umbrella, with higher lateral branching and 3-7 leaflets per compound leaf. It has a strong root system. The main roots that can go deep and the fibrous root system with multiple roots formed laterally are the plant’s safety nets against infertile and arid soil. It has a specific bud and flower structure. In an “on” year, the majority of fruit buds that yields the next year’s fruit fall off, due to insufficient cultivation conditions, unsuitable climate, infertile land and characteristics of the cultivar, which constitute the cause of periodicity. The pistachio is a dioic plant. In the pollination season, high relative humidity and excessive rainfall negatively affect fertilization. Parthenocarpy (unfertilized fruit formation) increases. The long pistachio group (Uzun, Kirmizi) that has the richest aroma and taste throughout the world and constitutes the majority of Turkey’s current produce, has green kernels when harvested early and has been the raw material of the dessert industry. The oval group (Siirt, Tekin) which has been increasingly produced in Turkey, is used in the nut industry. These cultivars can compete with the round group cultivated in Iran and USA with a much higher yield compared to the long cultivars. Pistachios are not highly selective in terms of soil requirement, but they are selective in terms of climate. Therefore, it does not grow in every climate. It requires a 4-month summer season at 25-30 ◦C for high-quality fruit after fertilization. Depending on the cultivar, the total temperature and chilling requirements of pistachios are 3607-4405 growing degree days and 750-1000 hours, respectively.