Walnut (Juglans regia L.) is one of the most important nutritional nut crops. Iran is considered as one of the centers for diversity and cultivation of walnut in the Middle East. In this investigation, 30 morphological traits were used to evaluate genetic potential of 100 walnut accessions. Results showed considerable phenotypic diversity in the studied walnut germplasm. High correlations were found among evaluated variables, e.g., positive correlations between nut and kernel characters. Principal components analysis revealed that traits related to shell texture, shell serrations, nut length, nut width, and kernel length accounted for a large proportion of the observed variability. UPGMA cluster analysis divided accessions into five different cluster groups. These groups mainly differed in nut and kernel traits. In the present study, 26 of the 100 studied accessions were trees possessing desirable qualities of late leafing, nut weight, kernel weight, light kernel color, and kernel ratio, and are recommended for cultivation. Furthermore, high morphological variability indicated that this germplasm includes rich and valuable plant material for future walnut breeding.
