Effect of Foliar Spray with Putrescine and Spermine on Morphological Characteristics and Yield Components of ‘Owhadi’ Pistachio

Pistachio is one of the most important horticultural products in the country. The presence of some physiological problems such as porosity and a decrease in the percentage of open nuts reduces the performance and quality of this product. The present study was conducted as a factorial randomized complete block design in 50-year-old pistachio trees of "Ouhadi" cultivar with five replications in 1397 in Rafsanjan. Treatments included foliar application of distilled water (control) and putrescine and spermine at concentrations of 0.1 and 1 mM, respectively. Foliar application was performed in two stages, full bloom (first stage) and six weeks after full bloom (almost before the hardening of the bony skin) (second stage). The results showed that the spermine treatment in the second stage of foliar application had the greatest effect on the total weight of fruit with spikes, fruit fresh weight, dry weight of 100 nuts and kernel weight of 100 fruits. The lowest percentage of fruit porosity was observed in 1 mM spermine treatment in the first stage of foliar application. The highest percentage of open fruits was related to the treatments of 1 mM spermine, 0.1 mM spermine and 1 mM putrescine in the second stage of foliar application. According to the results, it was found that the application of spermine in the second stage reduces the porosity and increases the percentage of splitted fruits and finally increases the yield of pistachio cultivar of Ouhadi cultivar.