Genetic Variation and Inheritance of Early Growth Characteristics in Three Wild Pistachio Populations

Pistacia atlantica is the most important tree species for the economy of many rural areas in west of Iran, but no effort has been made for the genetic improvement of this species. The aim of this investigation was to study the genetic variation and inheritance of early growth traits in P. atlantica. For this purpose, three wild pistachio populations comprising 60 randomly selected adult trees from northwest of Iran were sampled and half-sib seeds were sown in a forest nursery using randomized complete block design with three replications. During the growing season, plant height, collar diameter, number of leaves and sprout length were measured on the seedlings in 2009 and 2010. Analysis of variance based on split plot in time was carried out for the two-year data and squared phenotypic coefficient of variation (PCV2) were calculated for the above mentioned traits. Furthermore, additive genetic variance, narrow sense heritability and expected genetic gain were estimated among the half-sib families under study. In addition, phenotypic correlation coefficients of the traits from 30 two-year old seedlings with several characters of mother plants were calculated. Analysis of variance showed significant differences among trees for all of the seedling traits indicating the existence of enough genetic diversity within this species that can be utilized in breeding programs. Plant height and number of leaves had the highest PCV2 among the measured traits.Narrow sense heritability estimates were moderate for collar diameter (0.53), number of leaves (0.46) and sprout length (0.43) and high for plant height (0.71). Considerable genetic gain was also expected for plant height. In addition, plant height of half-sib progenies was significantly correlated with tree height, stem diameter and maximum seed diameter of mother plants. Therefore, plant height could be regarded as a reliable early selection index because of its high heritability and genetic gain and also, significant correlation with the characteristics of parental trees.