evaluation of some phenological and pomological characteristics of selected walnut genotypes from shahroud-iran

the first step in walnut breeding programs is to identify and evaluate superior genotypes of fruit trees. hence, there are various walnut breeding programs in various areas of iran. a study aimed to evaluate the morphological and chemical characteristics of selected superior genotypes of walnut was conducted in the shahroud region in 2011-2012.  the following genotypes were selected in this study as the best walnut genotypes:  x-18 homogamous genotypes due to desirable late leafing;   genotype x-11 for its high percentage of kernel production, easily removal of shell, thin shell; genotype x-52 due to its kernel plumpness compared to other genotypes, thin shell and high percentage of kernel and genotype x-70 for its kernel brightness, easily kernel extracting and high percentage of kernels. the x-49 and x-5 genotypes had the highest amount of linoleic and linolenic fatty acids and higher nutritional quality compared to other genotypes. three genotypes, x-3, x-11 and x-22, had the highest amount of oil. genotypes x-9 and x-45 had the highest amount of protein. the difference between oil content and fatty acid compositions was presumably due to genetic diversity and ecological conditions of the studied genotypes cultivation.