Comparison of thermal and thermomechanical methods of seed extraction from larch cones based on two case studies

Abstract

The paper analyzes two seed extraction methods used by Polish silvicultural seed extractories. The analysis involves cone batches as well as individual cones processed in extraction cabinets. During thermal extraction, the cones were dried (10 h), moistened with water (10 min), and dried again (10 h). During thermomechanical extraction, the cones were dried for a much longer time (40 h), and then crushed in a mechanical unit (20 min). The two examined cases of seed extraction were compared in terms of the size, weight, and moisture content of the cones involved, the steps in the extraction process, as well as the quantity and quality of the obtained seeds. Each of the extractories made use of cones of a different provenance, which differed significantly from each other. In order to compare the different seed extraction methods, the same batch of cones collected from one geographic locality should be used. The results of a process analysis show that the thermal method was superior in terms of energy efficiency and duration. The seeds extracted using the two methods were of the highest quality (class I), which indicates that in both cases the extraction process was conducted appropriately and did not cause the quality of the seeds to deteriorate. K e y w o r d s: scale kinematics, coniferous cones, seed extraction, quality assessment