Investigation of morphological diversity among native populations of walnut (Juglans regia) in Golestan province, Iran

Walnut is a plant belongs to Juglandaceae family. Among 21 species, of the
Juglans genus, the Persian walnut (Juglans regia L.) is recognized as the best
species. The main aim of the current research work was identification of genetic
diversity among Persian walnut species in Golestan province, Iran. Morphological
traits used as an approach to evaluate 96 trees which belonged to five native
populations. All morphological characters of leaf, flower and fruits were recorded.
Significant differences was seen among these populations in respect to character of
nut with husk and without husk. This range was between 14.88 to 55.88 gr for the
former and 5.64 to 25.91 gr for the latest one. Also the percent of kernel was in a
range of 19.95 to 50.19. Further results indicated a negative correlation between
high altitude with protogeny and percentage oil of kernels. Reversely, there was a
positive correlation between altitude and protein content of the kernels. Other
phenological traits such as seed biophysics and seed morphology (according to
IPGRI and UPOV descriptors) were evaluated within this study.