Physical Properties of Seeds of Eleven Fir Species

Abstract

Research Highlights: The correlations between the analyzed physical properties of seeds and seed mass were determined. The results were analyzed to determine most effective seed separation devices for the evaluated fir species. Background and Objectives: Information about the variations and correlations between the physical properties of seeds is essential for designing and modeling seed processing operations such as seed separation. The aim of this study was to determine the range of variations in the basic physical properties of seeds of selected fir species, and to identify the correlations between these attributes for the needs of the seed sorting processes. Materials and Methods: Terminal velocity, thickness, width, length, the angle of external friction and mass were determined in the seeds of 11 fir species. The measured parameters were used to calculate the geometric mean diameter, three aspect ratios, sphericity index and the specific mass of each seed. Results: The average values of the basic physical properties of the analyzed seeds were determined in the following range: terminal velocity – from 4.8 to 7.1 m s-1, thickness – from 1.76 to 3.22 mm, width – from 3.29 to 5.57 mm, length – from 5.44 to 11.06 mm, angle of external friction – from 26 to 33°, and mass – from 7.9 to 48.3 mg. The seeds of Sierra white fir where most similar, whereas the seeds of balsam fir differed most considerably from the seeds of the remaining fir species. Conclusions: Fir seeds should be sorted primarily with the use of mesh sieves with longitudinal openings to obtain fractions with similar seed mass and to eliminate the need for dewinging.

Physical Properties of Seeds of Eleven Spruce Species

“…This is consistent with the general practice of sorting seeds of forest trees and shrubs, where pneumatic separators are often deployed [27]. According to the literature [27,37,49,[59][60][61], pneumatic separators can be effectively used to sort the seeds of European beech (Fagus silvatica L.), European hornbeam (Carpinus betulus L.), small-leaved lime (Tilia cordata Mill. ), black locust (Robinia pseudoacacia L.), rowan (Sorbus aucuparia L.), grey alder (Alnus incana (L.) Moench), European silver fir (Abies alba Mill.…”

“…Germination rates and germination efficiency can be improved when these seed fractions are sown separately. Seed thickness also proved to be a more reliable separation trait than terminal velocity in studies of European beech [61], Norway spruce [49], and European silver fir (Abies alba Mill.) [58].…”

Variations and Correlations between the Physical Properties of Seeds of Eleven Spruce Species

“…This is consistent with the general practice of sorting seeds of forest trees and shrubs where pneumatic separators are often deployed [32]. According to the literature [32,42,54,[64][65][66], pneumatic separators can be effectively used to sort the seeds of European beech, European hornbeam, small-leaved lime, black locust, rowan, grey alder, European silver fir, Scotts pine, Norway spruce and European larch. However, a regression equation with the highest coefficient of determination (0.88) was obtained for the correlation between seed mass and seed thickness, which indicates that seed thickness (Figure 2) is the most reliable parameter for separating spruce seeds.…”

Influence of Scarification on the Germination Capacity of Acorns Harvested from Uneven-aged Stands of Pedunculate Oak (<em>Quercus robur </em>L.)

“…Symptoms of disease are also more visible in scarified acorns which can be removed from the batch. Unlike the seeds of other forest trees [43], pedunculate oak acorns cannot be sorted effectively based on physical parameters; therefore, the optical parameters of acorn cross-sections could be used as an innovative selection trait. Optical parameters cannot be reliably evaluated with a naked eye, which is why an automated scarification device with a vision system has been developed [8,24] to identify early symptoms of disease, eliminate damaged acorns and increase germination capacity by up to 10% relative to manually processed material.…”