Moisture content in dried forest tree seeds versus relative humidity of drying air
Research was carried out on drying of seeds of 15 orthodox forest tree species (Douglas fir, silver fir, European larch, mountain pine, Scots pine, Norway spruce, common birch, European beech, common ash, Norway maple, small-leaved lime, common alder, and elms: mountain elm, common elm and European white elm) in a temperature gradually growing from 20 to 60°C, which corresponded to the relative humidity of drying air ranging between ca 35% and ca 0.5%. The purpose of the research was to determine a mathematical relationship between relative humidity of the drying air and seed equilibrium moisture content which becomes stabilized after longer drying of seeds under constant temperature-humidity conditions. The relationship between dried seed equilibrium moisture content for most of the species (except fir) and relative humidity of the drying air can be described using regression equations (determination coefficient R2 oscillated between 0.71-0.96). Due to these equations, the level of drying air humidity needed for obtaining the required seed moisture content and planning the drying process can be calculated for the needs of forest management practice.
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