Determination of Persian walnut yield components and its correlation with phenological, morphological and biochemical traits

Estimation of correlation coefficients can accelerate walnut breeding programs and provide the ability to improve other traits along with targeted breeding traits. For this purpose, data obtained from two-year morphological evaluation of 325 screened genotypes from Fars, Mazandaran and Ilam provinces were used to study the correlation between morphological traits. In addition, in order to study the correlation between biochemical and morphological traits, biochemical characteristics of 52 superior genotypes out of 325 screened genotypes were evaluated for one year. Based on the results, a linear and strong relation was observed between phenological traits especially budbreak and harvest date. Yield had a positive and strong correlation with budbreak date (0.58**), nut weight (0.64**), kernel weight (0.46*), nut size (0.56**) and lateral bearing (0.53**) and a negative correlation with kernel color (-0.38*). Based on the result of stepwise regression analysis, nut weight, lateral bearing and nut size index were the main components of walnut yield. Correlation study between biochemical traits with altitude and morphological traits showed that oil and protein percentage of walnut kernel was not affected by the physical characteristics of the nut (nut and kernel size and weight). In Contrast, the oil and protein content increased with increasing altitude. A strong and negative correlation was observed between MUFA and PUFA. Also, PUFA: SFA ratio negatively correlated with shell thickness.