The selection of superior late-leafing genotypes of Persian walnut (Juglans regia L.) among seedling originated trees based on pomological characterizations

Abstract

The Persian walnut (Juglans regia L.) is widely cultivated in temperate regions of the world and is one of the most commercially important edible nuts. The present study was carried out to evaluate morphological variation of 302 walnut seedling genotypes and to select the superior late-leafing walnut genotypes. The genotypes studied exhibited significant differences based on the characters measured and 29 out of 41 characters showed the CVs more than 20.00% that indicated high variability among the genotypes. The genotypes were clustered into three groups based on leafing date, including early, moderate, and late. The selected late-leafing genotypes showed high pomological variations so that nut weight ranged from 5.18 to 15.88 g with an average of 9.93, and kernel weight ranged from 1.69 to 7.52 g with an average of 4.55. Also, kernel percentage varied from 28.18 to 59.47% with an average of 45.74. Kernel percentage showed significant and positive correlations with kernel length, kernel width, kernel weight, kernel filled, and kernel plumpness. The late-leafing genotypes selected were divided into two major clusters. Among the selected late-leafing genotypes, 16 selections were superior based on ideal values of commercial traits in walnut and are recommended for cultivation directly or use in breeding programs.