The Kinematics of Scale Deflection in the Course of Multi-Step Seed Extraction from European Larch Cones (Larix decidua Mill.) Taking into Account Their Cellular Structure

Abstract

The objective of the study was to elucidate the kinematics of cone opening in the European larch (Larix decidua Mill.) during a four-step seed extraction process and to determine optimum process time on that basis. Each step lasted 8 h with 10 min of water immersion between the steps. The study also described the microscopic cellular structure of scales in cones with a moisture content of 5% and 20%, as well as evaluated changes in cell wall thickness. The obtained results were compared with the structural investigations of scales conducted using scanning electron microscopy (SEM) of characteristic sites on the inner and outer sides of the scales. The greatest increment in the scale opening angle was noted on the first day of the process (34°) and in scales from the middle cone segment (39°). In scales with a moisture content of 5% and 20%, the greatest changes in cell wall thickness were recorded for large cells (57%). The inner and outer structure of scales differed in terms of the presence and size of cells depending on the moisture content of the cones (5%, 10%, or 20%). The study demonstrated that the moisture content of cones was the crucial determinant of the cellular structure and opening of scales in larch cones. The scale opening angle increased with decreasing moisture content but did not differ significantly for various segments of cones or various hours of the consecutive days of the process. This finding may lead to reducing the seed extraction time for larch cones. The internal and external structure of scales differed depending on moisture content, which also determined the size and wall thickness of cells.

The cracking of Scots pine (Pinus sylvestris) cones

“…We therefore assume the seed release of P. sylvestris to be tailored to allow for good seed dispersal and a successful seedling establishment while at the same time it enables maximized protection against threats to the day of seed release. Future investigations could be extended to include the opening process of cones from other conifer genera (e.g., Aniszewska, 2010 ; Tulska et al., 2021 ).…”

Optimization of the process of seed extraction from the Larix decidua Mill. cones including evaluation of seed quantity and quality

“…A failure to sufficiently reduce the moisture content of cones during the extraction process prevents seed movement within the scales 18 . For a long time now researchers have been studying phenomena involving wood that can adopt a deformed shape at a certain moisture content and then return to its original shape after absorbing water 51 – 53 as well as scale movements in conifer cones caused by their cellular structure 54 – 59 . Findings from such research can form the basis for analyzing multi-phase movement by artificial intelligence 60 , 61 .…”

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

“…The seeds obtained using the studied methods were placed in a Jacobsen germinator (Laborset, Łódź, Poland) in four 100-seed replicates, using the same laboratory equipment used in other studies (Tulska et al, 2021). Germination energy was measured on day 7 and germination capacity on day 21 of the experiment, which was the basis for the seed quality classification (PN-R-65700; ISTA, 2018).…”

“…The process of seed extraction from larch cones takes longer than that for other cones of forest conifers (Aniszewska, 2008) due to their specific structure (Tulska et al, 2021;Tyszkiewicz, 1951;Song et al, 2015), it involves the seeds being ejected gradually in several kinematic cycles of scale opening and closing (Załęski, 2002;Martone et al, 2010;Poppinga et al, 2017). There are three groups of activities for seed extraction from larch cones in extractories.…”