variation in some european pear (pyrus communis l.) seedling rootstock populations using morphological chracteristics

many characteristics of pear trees such as growth, fruit size and yield, are influenced by the genetic characteristic of the rootstocks. in iran, mainly european pear seedlings (pyrus communis l.) are used as the rootstock in the pear orchards. thus, evaluation of pear seedling rootstocks is an important task. this experiment was conducted in 2009 and 2010 growing seasons in order to explore the genetic diversity of 105 rootstock seedlings originated from two pear seedling populations from mashhad and karaj regions. seedling rootstocks assessment was performed based on differentiation, uniformity and stability tests (dus) of pear. results showed significant differences (p≤0.01) in the height and trunk diameter increase, between karaj and mashhad seedling populations. however, significant correlation between the seedlings height and growth vigor (r = 0.68) and trunk diameter (r = 0.43) was also observed. cluster analysis, classified the seedlings into 30 groups, so that, 10 and 12 groups belonged to mashhad and karaj populations genotypes, respectively. two pear seedling populations (mashhad and karaj genotypes) were successfully separated by cluster analysis. based on the sum of the results, high variation for all measured characteristics were observed in two rootstock seedling populations.