The annual consumption of soil potassium by pistachio trees is high. Since the clay soil absorbs potassium, the amount of potassium that can be exchanged or used by the tree in the soil solution is little, and every year this deficiency must be compensated by fertilizers. To evaluate the role of potassium in improving the nutritional elements of the leaves and nuts of two pistachio cultivars (‘Ahmad-Aghaei’ and ‘Kalleh-Qoochi’), four levels of potassium fertilizer were used (0, 200, 300 and 400 mg of potassium per liter of irrigation water) in a factorial experiment in the form of a randomized complete block design with three replications. This experiment was performed on the ON and OFF branches in 2017 and 2018. The results showed that the application of potassium increased the amounts of nutritional elements in the leaf and nut. Specifically, the amounts of nitrogen, phosphorus and potassium were higher in the leaves of OFF branches, whereas the concentrations of calcium and magnesium were higher in the leaves of the ON branches. In both cultivars, the application of potassium increased the amounts of nitrogen and phosphorus in the leaf, as well as the potassium content in the nut. The amounts of calcium and magnesium in the leaf and the amount of calcium in the nuts were higher in the Kalleh-Qoochi cultivar. This treatment can be recommended when plants are in their OFF year, so that potassium can be reserve into the tissues until the ON year. Manuscript profile

Pistachio is one of the important horticultural crops, comprising 6.4% of the agricultural exports of Iran. In this study, the genetics of some early growth traits of 40 pistachio genotypes was evaluated under a greenhouse setting. The 40 genotypes were created by crossing eight male trees with five female individuals using the North Carolina I mating design. The experimental design was a completely randomized design (CRD) with three replications established in the greenhouse. Seedlings were assessed for stem height, number of leaves, roots, and shoot dry weight. The results revealed significant variation for the phenotypic traits assessed among the male parents. Male M6 had the lowest height among the genotypes. Males M4 and M2 had the highest and lowest number of leaves, respectively. The offspring of male M7 had maximum shoot and root dry weight. The offspring of females within males were significantly different. Regarding all studied traits of hybrids plants derived from (male M7×Fendoghi-48) had the highest height, leaf number and shoot dry weight. So M7 was the best male for mating and selection for good early seedling growth in pistachio because genotypes with a taller stem had better vegetative growth which can be used for producing rootstocks. For all studied traits, the amount of additive variance was greater than dominance variance, and shoot dry weight had the highest narrow-sense heritability (0.518) and the most expected relative genetic gain with 10% of selection intensity, indicating that the selection can be used to improve these early growth traits in pistachio. Manuscript profile