Genetic Analysis of Early Growth Characteristics in a Pistachio (Pistacia vera L.) Population Raised under Greenhouse Conditions for use in Breeding Program

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.