The simplest method of improving seed quality involves the elimination of non-germinated or damaged seeds from the propagating material. The aim of this study was to determine correlations between the basic physical properties of black alder achenes and their germination capacity to generate valuable data for improving the seed material. The experiment was performed on 5 batches of achenes harvested from tree stands in 4 seed zones in 3 forest regions of north-eastern Poland. The thickness, width, length, angle of sliding friction and mass of every achene were measured. The results were used to calculate the geometric mean diameter, aspect ratio and sphericity index of black alder achenes. Achenes were germinated for 28 days, and the results were recorded daily to determine the germination rate index of every achene. The relationships between the examined parameters were determined in a t-test for independent samples and by correlation analysis. The analyzed physical parameters of achenes had a minor impact on their germination rate. The results indicate that the classification of black alder achenes based on all measured parameters would not significantly contribute to germination uniformity. The fraction of longest or widest achenes had higher potential germination capacity than unsorted achenes. Germinated achenes were generally characterized by greater thickness, width, length, mass, geometric mean diameter, aspect ratio and sphericity index, but lower angle of sliding friction in comparison with non-germinated achenes.

Keywords: dimensions, mass, angle of sliding friction, germination, correlation.