Study on the Seedbed Density of Growing Slash Pine Seedling

The bareroot seedling quality of slash pine(1～0) grew at different nursery density levels was studied,and their economic benefits analyzed. It showes that seedbed density is a decisive factor to seedling quality which decreases with the increase of density. The yield of grade l seedling are the highest at 111/m2,and the nurnber of grade 2 and 3 seedlings increase by larger density,the percentage of the grade 3 seedling reach 15% of the permissive limit of the national seedling production standard at 167/m2. If only grade 1 seedling in qualified,the output/input is the highest at 69/m2; when grade 1 and 2 seedlings are used for plantation and give different prices, the output/input is highest at 111/m2. The practice of outplanting the ungraded seedlings(grade 3) which leads to higher density,at which the benefit of production is highest but the seedling quality is worst.A comprehensive survey of seedling quality, yield of qualified seedling and the economic benefit has been made,and the rational seedbed density would be 70～110/m2.