Evaluation of genetic diversity of some walnut genotypes based on morphological characteristics in Khorasan Razavi province

Identification, protection, and use of genetic resources as one of the most valuable national assets of each country are of particular importance. Persian walnut (Juglans regia L.) due to having multiple uses (food, wood, conservation, genetic, and medicine) is one of the most valuable genetic resources of Iran. For this reason, 16 quantitative traits and 6 qualitative traits of tree, leaf, and fruit of walnut were studied on 56 genotypes during 2013-2015. The results obtained from quantitative traits showed that leaf length varied from 24.43 to 53.83 cm, leaf width from 21.94 to 39.03 cm, kernel weight from 4.12 to 10.30 g, dry fruit weight from 12.72 to 26.78 g. Genotypes ES10 and ES41 were determined as the earliest and latest leafing genotypes, respectively. Genotypes ES39, ES41, ES43, and ES46 were identified as superior genotypes due to having many desirable characteristics such as late leafing and high quality of the kernel and fruit. It is thus better to propagate these superior genotypes for cultivation in the province, but along with it, other genotypes must be kept in a collection to prevent the risk of extinction of this strategic product by preserving the diversity. In the future, this high diversity, which is the main pillar of breeding science, can be used for the production of more resistant and higher quality cultivars by using the breeding technique.