Using Taguchi as a New Method to Optimization of Nutritional Requirement of Pistachio (Pistacia vera)

Pistachio is one of the most important horticultural products of Iran. It has long been considered a strategic non-oil export product. Thus, it is necessary to consider the factors which affect the performance of this product per unit area. The present study aims to examine the effect of different levels of common fertilizers used in pistachio orchards on pistachio yield and quality characteristics, and optimization of chemical fertilizer through the Taguchi method. This research was accomplished at the Yazd University during 2018–2019 by using the Taguchi method for the first time in the world. By optimizing the Taguchi method, the optimum level of fertilizer consumption for some effective nutrients was determined. To this end, four fertilizers (urea, triple superphosphate, potassium sulfate and calcium nitrate) at four levels and three fertilizers (zinc chelate, iron chelate and manganese chelate) at two levels according to Taguchi scheme (L16) were selected. The variables studied in this research were total yield, ripening percentage, split percentage and blankness. The results determined the optimum level of each fertilizer used for each variable (150 kg/ha Calcium nitrate for the total yield, 300 kg/ha triple superphosphate for the fruit ripening percentage, 150 kg/ha Calcium nitrate for the fruit split percentage and kg/ha 200 urea for blankness). We could use the Taguchi method for the determination of nutritional requirements of pistachio because using too much fertilizer will cause salinity increasing in cultivated areas of pistachio as well as will increase production expenses. This method can help predict and determine the most important fertilizers which affect the quantity and quality of pistachio yield and the optimum amount of fertilizer.