Attributes of easy kernel removal in some Persian walnut (Juglans regia L.) genotypes using path analysis

Abstract

This research was conducted to find the most significant variables affecting easy removal and color of the kernel in Persian walnut. Twenty-six botanical traits and fruit characteristics were employed to select fourteen walnut genotypes for analysis. Results of simple correlation analysis indicated significant positive correlation of ease of kernel removal and color with female bloom date, apex shape of nut, kernel shrivel and shell strength. On the other hand, nut shape and husk thickness indicated negative significant correlation with easy removal of the kernel and its color. Stepwise regression was applied to eliminate the effects of non-contributing characters and characters with low impact on ease of kernel removal and its color. The ease of kernel removal was significant in relation with shell strength, leaf width, female bloom date and shape of apex, with a coefficient of determination of 94%. Kernel color showed association with kernel shrivel, husk thickness and shell strength with a correlation coefficient of 0.84. Path analysis revealed highest positive direct effect of shell strength on ease of kernel removal. Comparison of direct and indirect effects on kernel color, indicated the highest negative direct effect was related to kernel shrivel on kernel color. Comprehending the relation between nut and kernel traits would be an appropriate guide for breeder to improve kernel quality in walnut.