The physical properties of forest tree seeds are an important consideration in seed cleaning and sorting processes. In order to determine variations in and correlations between the pairs of the following parameters: the terminal velocity, thickness, width, length, mass and angle of static friction on steel were measured for seeds of seven deciduous tree species (common beech, copper beech, common hornbeam, small-leaved lime, black locust, mountain ash and grey alder). The results of measurements were processed statistically by correlation analysis and linear regression analysis. Seed mass was most highly correlated and angle of static friction was least correlated with the remaining parameters. The highest value of the correlation coefficient and the equation with the highest value of the coefficient of determination were reported for the relationship between the mass and terminal velocity of small-leaved lime seeds. In view of the above, a pneumatic separator is recommended for separating seeds of the above tree species. A pneumatic separator is also an effective device for separating the seeds of common hornbeam and grey alder. Common beech and mountain ash seeds should be separated with the use of mesh screens, and copper beech and black locust seeds should be separated with the use of a seed grader.

Keywords: seeds, physical properties, processing, seed quality.