Morphological evaluation and identification of walnut (Juglans regia L.) superior ‎genotypes in north Hamadan province of Iran

The current research was conducted to evaluate the phenological, morphological and pomological diversity of some selected walnut genotypes in the north of Hamadan province during 2016-2017 growing seasons. For this purpose, 84 mature walnut genotypes were selected and evaluated based on the IPGRI and UPOV descriptors. After two years of evaluation, 12 genotypes were selected as the superior genotype. The results showed that HaRaToMa23 genotype is a late-leafing genotype with 23 days delay in compare with the reference standard genotype. In addition, three genotypes including HaRaSuSh1, HaRaToMa24 and HaRaVaAh17 were homogeneous.In term of pomological studies, nut and kernel weights and kernel percentages of superior genotypes varied from 12.95-22.60 g, 6.82-11.56 g and 47.15-59.47 %, respectively. The lowest shell thickness (0.77 mm) was among the superior genotypes above for HaRaVaAh9 genotype. Also, HaRaSuSh1 genotype had the highest nut and kernel weight and HaRaSuSh2genotype showed the highest kernel percentage. The selected superior genotypes had a lateral bearing habit and their kernel color varied from bright to very bright that was easily distinguished from the hard skin. Based on the results, a positive and significant correlation (r = 0.96 **) was observed between leafing date and harvesting date, tree yield and nut weight (r = 0.63 **) and lateral bearing rate (r = 0.73 **) at a probability level of 1%. Selected superior genotypes in terms of many important breeding traits showed superiority in compare with commercial cultivars, so these selected genotypes can be used in breeding programs to introduce new cultivars.