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红松换床育苗培育年限较长、费工、占地,所以目前各地多采取留床育苗。红松播种一般每亩播种量都在400斤以上,在正常情况下每亩当年可产幼苗20万株左右。经过二年留床之后,满三年生时每亩只能产合格成苗8万株左右。大约有60％的幼苗,在二年留床过程中由于生存竞争而被淘汰。三年留床合格成苗,虽然苗高、地径都达到了出圃标准,但生长纤弱、径高比小、根系不健全(见照片1),所以造林成活率很低。我场在1979年利用红松留床苗造林,因苗木质量不好,成活率仅有50％左右。
Korean pine bed nursery for a longer period of incubation, labor, land area, so at the moment to take more bed nursery. Pinus sylvestris planting generally per acre sowing more than 400 pounds, under normal circumstances can produce 200,000 mu per year or so. After two years stay bed, full three years of birth per acre can only produce about 80,000 qualified seedlings. Approximately 60% of the seedlings are eliminated due to survival competition during the two-year bed storage. Three years stay in bed qualified into seedlings, although the height of seedlings, ground diameter have reached the standard, but the growth of weak, small diameter ratio, the root system is not perfect (see photo 1), so afforestation survival rate is very low. My field in 1979 to use Korean pine bed seedlings afforestation, poor quality of seedlings, survival rate of only about 50%.