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Mechanical seed extraction of lodgepole pine MacAulay, James Donald

Abstract

Seed extraction from serotinous lodgepole pine cones (Pinus contorta var. latifolia Englem.) was investigated to identify the physical properties and characteristics which affect seed extraction by both conventional kiln drying techniques and by mechanical means. This information provided a basis for systematic design of specific processing tools for a portable continuous flow mechanical seed extraction system. Cone scale deflection was characterized and its effect on seed release is reported. The effect of moisture content upon scale stress relaxation during storage and subsequent reduction in seed release is discussed. Flash heating of cones in hot water and hot gas was found to effectively release serotinous seals without incurring thermal seed damage. Two continuous flow flash heating seal breaking tools were designed and tested. A flame seal breaker proved most suitable for commercial operation, and this tool was calibrated for use on both young and weathered cones. Mechanical seed extraction by cone core removal was effective, but asymmetrical cones prevented accurate core boring, thus resulting in considerable seed destruction. Seed extraction by threshing also was effective. Testing of first and second generation threshing tools was carried out on lodgepole pine, Douglas fir, white spruce and western hemlock. Further study is recommended to identify the optimum values of the many biological variables, machine variables and operating conditions which affect cone threshing.

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