Investigation of genetic diversity of Juglans regia using quantitative and qualitative growth traits

Persian walnut (Juglans regia L.) is an economically important species cultivated worldwide for its wood and nuts. Walnut has high genetic diversity due to sexual reproduction and cross-pollination. In this study, the Genetic diversity of walnut was investigated from the wood production viewpoint. In 1999, the walnut seeds of straight and good quality trunk mother trees of three regions including Karaj (10 seeds), Baft (22 seeds) and Isfahan (22 seeds) were planted in the Forests and Rangelands Research Institute, Iran. During 1996 and 1997, the vegetative traits of 17-18 years old walnut trees, including collar diameter at 30 cm height, stem shape quality, tree height, canopy area, diameter at breast height, wood volume production and mean annual height growth were studied. Analysis of variance of studied traits indicated that there was a significant difference between regions in stem shape, canopy area and diameter at breast height. Study of different regions showed that the trees with Baft origin had higher height (3.27 m), canopy area (7.47 m2) and mean annual height growth (17.77 cm) than other Regions. However trees with Karaj origin had higher diameter at breast height (9.37 cm). The UPGMA dendrogram grouped genotypes into two groups. Genotypes of group 1 had higher wood production; however genotypes of group 2 showed higher wood quality. The results indicate considerable genetic variation among genotypes that can be useful in walnut breeding programs.