The possible role of macroelement content on bud abscission in pistachio (Pistacia vera L.)

Pistachio is the economically important nut tree in Turkey. Alternate bearing is one of the most important problems in pistachio, and it has a negative effect on producers, consumers and the country's economy. The cultivar 'Uzun' is one of the most important commercial pistachio cultivars in Turkey, and it has strong tendency to alternate bearing. There are no nuts completely in “Off” year while the trees are highly productive in the following year (“ON” year). The physiological mechanisms of the bud abscission process caused alternate bearing is unknown. In this study it was aimed to detect a relation between nutrient uptake and alternate phenomena in the pistachio 'Uzun' cultivar. For this purpose, nutrition concentrations were determined in various physiological periods from full flowering to harvest in one year old shoots of 'Uzun' pistachio cultivar under arid conditions. The shoots were compared based on their N, P, K, Ca and Mg content on shoots of “ON” and “OFF” year trees separately. According to the results, N, P, K, Ca and Mg contents of shoots were changed in “ON” and “OFF” year shoot samples and varied during the developmental stage and generally N, Mg and Ca elements were detected higher in shoots of “ON” year trees, while P and K, higher in “OFF” year trees.