The Relationship Between Size and Type of Shoot with Fruit Bearing in Some Pistachio (Pistacia vera L.) Cultivars Under Khorasan Razavi Climatic Conditions

In pistachio flower buds is formed on the lateral and terminal branches of current growth and bearing happens on one-year-old branches. To achieve higher yield, the production and selection of the best bearing shoots is important in the orchard management. The aim of this research was to explore and determine the relationship between size and type of shoot with fruit bearing in some pistachio (Pistacia vera L.) cultivars under Khorasan Razavi climatic conditions. This research was carried out using randomized complete block design with three replications in 2012 and 2014 in pistachio collection orchard at the pistachio research station of Feizabad, Khorasan Resavi province, Iran. Three pistachio cultivars including: Abbasali, Akbari and Badami-Sefid were evaluated. The results showed negative significant correlation between diameter of terminal shoot and the number of nuts on cluster of terminal branch (r = -0.67*), and between the number of flower buds on lateral shoot and the weight of flower bud on lateral shoot (r = -0.64*). There was also negative significant correlation between the percentage of blank nut and the weight of flower buds on terminal shoot (r = -0.78*), and between the number of flower bud on terminal shoots and the weight of dry nut in terms of ounce (r = -0.84**). On the other hand, there was positive significant correlation (r = 0.79*) between lateral shoot length and the number of flower bud. The effect of year on the number and length of lateral shoots, diameter of terminal shoots, abscised flower buds on lateral shoots, the weight of flower buds on the terminal and lateral shoots and the weight of nuts was significant (P < 0.01). There was not significant correlation between diameter and length of terminal shoots and the number of flower buds, but there was positive correlation between lateral shoot length and the number of flower buds. Therefore, any orchard management prectices that prevent the excess growth of terminal shoots and also increase the growth of lateral shoots will lead to increasing pistachio yield. In conclusion, the results of this research will be useful for the orchard management and suitable pistachio trees pruning for higher yield.