Evaluation of genetic potential of walnut germplasm in Urmia region for selection of superior genotypes with lateral bearing habit

Identification and evaluation of superior and native genotypes of fruit trees is of great importance in maintaining germplasm and breeding programs. Many fruit cultivars are selected from local genotypes. In order to evaluate the genetic diversity of walnut genotypes in Urmia city, 42 high-yielding genotypes were selected from different parts of the city and together with Chandler cultivar were evaluated in terms of important phenological and morphological characteristics of the fruit. Traits such as weight, length, width of fruit, skin thickness, kernel color, ease of kernel separation, leaf opening time, and opening time and completion of male and female flowers were measured according to walnut description. Based on the results, it was found that there was a high diversity in the evaluated characteristics between genotypes. Dry fruit length between 27.06 to 47.20 mm, fruit width between 24.60 to 38.80 mm, fruit dry weight between 5.63 to 13.83 g and kernel dry weight between 2.76 to 13.7 g were variable. Genotypes of 7, 11, 29, 30, 35, 36, 40, 41 and 42 had the highest weight and ratio of kernel to fruit. Also, genotypes 30 and 9 had the lowest thickness of wood bark with 0.76 and 0.80 mm, respectively. Based on the results of dual correlation of traits, significant positive and negative relationships were observed between the evaluated traits. Cluster analysis based on all the evaluated traits by Ward method could place the studied genotypes in 3 main groups. Based on the results of the present study, a good diversity was observed among the studied genotypes, which indicates the high potential of walnut germplasm in Urmia region to select superior genotypes that are compatible with the ecological conditions of the region.