The Use of Clear Polythene Cloches to Improve the Growth of One-Year-Old Lodgepole Pine Seedlings

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Abstract
Unsterilised nursery seedbeds, prepared in a conventional manner and sown with lodgepole pine ( Pinus contorta Dougl. ex Loud, ssp contorta ) were covered with clear polythene cloches, with or without the edges buried, from the date of sowing for 0, 8, 16 and 21 weeks. Germination rate and numbers of seedlings germinating were increased by all the cloche treatments. Deaths of seedlings under cloches with unsealed edges were greater than for the cloche treatments with completely buried edges. Due to increases in both stem unit number and stem unit length, the cloche treatments increased height growth in proportion with duration of cloche cover. Seedlings covered for 16 or 21 weeks were over 3 times the height of the controls and almost all were over 10 cm but they were not sufficiently sturdy for forest use. The use of polythene cloches for the production of seedlings suitable for lining-out or forest planting is discussed.