Physical characterization of cotoneaster seeds to improve sorting efficiency

Shrubs are an important component of tree stands, particularly in species-poor habitats. Ornamental shrubs have considerable visual and esthetic appeal and are often planted in the vicinity of industrial sites. Flowering shrubs of the genus Cotoneaster belong to this category of plants. The physical attributes of cotoneaster seeds have never been investigated in the literature. Therefore, the aim of this study was to characterize the basic aerodynamic, geometric, frictional, and mass properties of the seeds of selected cotoneaster species and to determine the correlations between these parameters to facilitate seed sorting operations. Physical properties of seeds of five species of cotoneaster (Diels', Hjelmqvist's, hollyberry, showy, and wall) were determined. The strength of the correlations between seed mass and the remaining seed parameters was evaluated. Showy cotoneaster produced the largest seeds and Diel's cotoneaster the smallest. Seed mass was most highly correlated with terminal velocity in Diels', Hjelmqvist's, and wall cotoneaster seeds, whereas the mass of hollyberry and showy cotoneaster seeds was bound by the strongest correlation with seed thickness. These observations indicate that cotoneaster seeds should be divided into uniform fractions with the use of pneumatic separators or mesh sieves with longitudinal openings. These devices can decrease the coefficient of variation of seed mass by around 5% to around 62% in different seed fractions. The variations in seed mass were most effectively reduced in showy cotoneaster (by approx. 57% on average) and least effectively reduced in hollyberry cotoneaster (by approx. 13% on average).