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Abstract This study aimed to exploit the genetic diversity of walnut populations in Joveyn region, Northeastern Iran. Phenological and pomological characteristics of 135 out of 500 genotypes were evaluated for two consecutive years (2021–2022) based on UPOV and IPGRI descriptors. The results showed that nut and kernel weight and kernel percentage ranged between 6.81–17.29 g, 3.06–8.24 g, and 38–59%, respectively. The highest nut weight belonged to genotype 21KH-JC14 with an average of 16.88 g, while the lowest belonged to genotype 21KH-A88 with an average of 6.99 g, over two years. The highest kernel weight was recorded for genotype 21KH-JC16 with an average of 8.78 g over two years, while the lowest kernel weight with an average weight of 2.3 g belonged to genotype 21KH-A88. The budbreak date of the earliest and the latest genotypes were 1 and 17 days after the reference standard, respectively. The harvest date of the earliest and the latest genotypes, were 2 and 15 days after the reference standard, respectively. Based on the results of the two-year phenotypic evaluation, according to leafing date, yield, lateral bearing, nut weight, and kernel quality, five genotypes, including 21KH-JC1, 21KH-JC9, 21KH-A94, 21KH-BK66, and 21KH-J131, were selected as the superior genotypes and were re-evaluated for phenotypic evaluation. The nut weight, kernel weight and percentage of the selected superior genotypes ranged between 14.87–16.45 (g), 7.43–8.4 (g), and 47-51.09 percent, respectively. These genotypes had desired shell thickness with large nut size and light kernel color which was easily removed from the shell. Overall, these selected superior genotypes can be used in further field trials and walnut breeding programs.
Hamidirad et al. (Mon,) studied this question.