Interaction effect of sodium benzoate, potassium nitrate, soybean oil and volk oil application on elimination of chilling requirement of pistachio trees

The global warming in recent years and chilling requirement deficiency of pistachio trees caused a considerable reduction in quantity and quality of the pistachio nut. To evaluate the role of chemical on overcoming on chilling requirement deficiency of pistachio (Akbari cultivar), this research was carried out in Anar and Koshkooeieh regions, Rafsanjan, Kerman, during two years using a randomized complete block design with three replications. Experimental treatments included volk oil 4 and 6%, soybean oil 4 and 6%, potassium nitrate 4 and 8 per thousand, volk oil 4% + sodium benzoate 4 per thousand, volk oil 3% + sodium benzoate 1 per thousand, volk oil 4% + sodium benzoate 1 per thousand, volk oil 2% + soybean oil 2% + potassium nitrate 5 per thousand + sodium benzoate 0.5 per thousand, volk oil 3% + soybean oil 3%, volk oil 4% + potassium nitrate 5 per thousand,  soybean oil 5% + potassium nitrate 5 per thousand + sodium benzoate 1 per thousand, volk oil 5% + potassium nitrate 5 per thousand + sodium benzoate 1 per thousand as well as control. The amount of sodium and potassium (in the flower buds and open flower), nutrients in leaves tissue (iron, copper, zinc, phosphorus, sodium, potassium and manganese), weight of 100 nuts, splitting nut percentage, blank nut percentage, ounce rate and fresh crop weight per tree were measured. The results showed that the maximum of splitting nut percentage and the minimum of blank nut percentage were observed in treatments of volk oil 4%, volk oil 6% and volk oil 3% + sodium benzoate 1 per thousand. There was not significant different between experimental treatment in the amount of iron, copper, zinc, phosphorus, sodium, potassium and manganese in pistachio leaves. The final results showed that soybean oil  6% and sodium benzoate 0.1% + potassium nitrate 0.5% + volk oil 5% decreased ounce rate 1.38 and 1.01, blank nut percentage 3.5 and 2.28  and increased weight of 100 nuts 7.1 and 5.6 gr, fresh crop weight per tree 2.8 and 7 kg in comparison with control respectively.