Pomological and Phenological Identification of Some Walnut (Juglans regia L.) Genotypes and Cultivars

The Persian walnut (Juglans regia L.) is one of the most valuable crops in Iran. The present study was conducted in The rabor agriculture research station (RARS) in Kerman province to investigate 21 important pomological and phenological variables among 37 walnut native genotypes and commercial cultivars in the year 2020. In general, results showed that walnuts from RARS were phenotypically diverse with the significant variation found across most traits examined. The highest and lowest coefficient of variation (CV) was for kernel percentage (CV= 29.48%), and time of male flowering (CV= 14.77%), respectively. Results also showed a strong positive correlation between nut weight and kernel weight (r= 0.727). The date of nut maturity had the lowest correlation with kernel intensity of  the ground color (r= -0.476). Principal component analysis of variables revealed that the first eight principal components (PCs) accounted for 79.43% of the total variation. Cluster analysis based on variables produced a dendrogram with five main clusters. The grouping of genotypes was not following their geographical origin. This study revealed the presence of high phenotypic diversity in the walnut genotypes of Rabor Agricultural Research Station (RARS), supporting their breeding value for possible use in the future.