Genetic diversity based on morphological traits in walnut (Juglans regia L.) landraces from Karakoram region-I

Walnut is one of the most important nutritive nut crops and widely grown in Gilgit-Baltistan region of Pakistan. In the present study 19 local landraces were analyzed for morphological traits to investigate genetic diversity and identify promising landraces for cultivar development. Multivariate analyses showed high variation for morphological traits and nut and kernel characteristics. Cluster analyses depicted diversity among the local land races which separated them into 2 major clusters groups, showing more association to morphological differences. PCA revealed that the 1st four principal components (PCs) possessed Eigen value >1.0, where PC1 and PC2 contributed total variance of 41.65 percent and 23.42 percent respectively with total variance (65.05 percent) showing maximum factor loadings by kernel ratio, shell percent, kernel yield and nut width by the first two PCs. Pearson correlation coefficient among walnut landraces revealed positively significant correlation between shell yield and nut weight(r=0.96), kernel yield and nut width(r=0.85), whereas negative correlation were observed (r = -0.89 and r = -0.76) between kernel ratio with shell yield and nut weight respectively. A wide range of diversity was observed among the local landraces from Karakoram regions and the landrace HKK and GNAG were reported as promising one with highest kernel ratio. These landraces are potential for future breeding of nut crops with distinct morphological traits. (author)