Effect of concentration and the time of foliar application of Epibrassinolid on flower buds and fruit abscission and some morphological and physiological parameters of pistachio tree (Pistacia vera L. cv. Ahmad- Aghai)

Flower buds and fruit abscission, production of blankness, non-split and deformed nuts are the most important physiological disorder in pistachio trees. The importance of plant growth regulators in alleviation of these disorders has been proved. In this project the effects of Epibrassinolid on alleviation of some of these problems in “Ahmad- Aghai” cultivar has been studied. The experiment was performed as factorial based on completely randomized design with 3 replicates in a commercial orchard at Rafsanjan (Kerman Province). The treatments consist of 0 (control), 0.5 and 1 (mg ml-1) epibrassinolid treatment in two stages (before and after full bloom). 0.5 (mg ml-1) epibrassinolid decreased the bud and fruit abscission while increased the fresh and dry weight and yield of branches. Epibrassinolid in the first stage decreased the blank fruit production and increased the split fruits. Epibrassinolid treatment obviously decreased the amount of ethylene in fruits while it had no significant effect on morphological characteristics. 0.5 mg ml-1 epibrassinolid was the best concentration and the first stage (a week before full bloom) was the best time for treatment in Ahmad- Aghai cultivar trees.