Abstract Studies of physiological diversity and its effect on the expression of traits in plants are used in breeding programs as a selective tool with the aim of selecting special attributes for creating a new product. In this study, the correlation coefficients among 17 horticultural traits of 34 genotypes from 11 different places of Semnan province were examined. A significant positive correlation was observed between fruit weight and kernel weight, susceptibility to blight and leaf abscission, leafing date and female flower emergence and between kernel percentage, kernel weight and kernel plumpness. Furthermore, a significant negative correlation existed between harvest time and tree vigor, fruit shape and fruit weight and kernel percentage with shell thickness. The most important characteristics that had a direct impact on kernel percentage were shell thickness and kernel plumpness. The attributes that were effective on fruit ripening were tree form, catkin emergence time and shell thickness. However, the residual effects suggested that there might be other important determinant traits for harvest date, which were not considered in this study.

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