Polymorphism study of local walnut population

A walnut polymorphism study has been done according to the results of expedition observation of 320 coeval plants in a local walnut (Juglans regia L.) population in different soil-climatic conditions of foothills and plains-steppe zone of the Crimea. During the investigation, the following morphological indicators have been determined: blossom time of male and female flowers; type of fruiting; fruit – shape of longitudinal section in three directions, size and mass; ripening period; kernel – mass, fullness and percentage; shell – color, structure of surface, thickness, integrity; leaf fall time. Except this, the level of walnut resistance to negative air temperatures in winter was taken into consideration. Determination of walnut cultivars to winter resistance has been done according to a method worked out in Nikita Botanical Gardens (Rihter, 1981). Evaluation of winter resistance has been done using the method of Lapin and Ryabov (1982). The obtained results testify that the high level of heritability is typical for the following characteristics: leaf fall time – 68%, type of flowers – 89%, number of male inflorescence – 84%, fruit mass – 86%, kernel mass – 76%, kernel color – 62%, structure of shell surface – 86%, kernel size – 84%, fruit form – 76%, shell integrity after fruit abscission – 70% and shell thickness – 64%. All morphological characteristics of the fruits were well correlated with each other. Positive correlations between kernel mass and fruit mass (r=0.82) and kernel mass and shell thickness (r=0.99) have been determined. A high positive correlation has been determined between fruit mass and its linear proportions. This research allows us to determine the metameric variability of the walnut morphological characteristics within the plant crown. Among the determined morphological characteristics of walnuts for studied plants, linear sizes (v=2.51-11.2) were the most constant and fruit mass (v=26.4) was less constant. The most variable character was the kernel percentage (v=18.4).