Density And Row Spacing On Seedling Of Populus Tomentosa

The quality of seedlings affects the outplanting performance directly,meanwhile the seedling density and row spacing affect the quality and yield of seedlings.This study aims to explore the response of Populus tomentosa growth,nutrient content and light interception to density and row spacing.Three seedling densities(50000(A1)?41667(A2)?3 1250(A3)seedling/hm2)and three kinds of row spacing(uniform row Bi(row spacing 0.8 m),the large narrow-wide rows B2(row spacing 0.6+1 m),and the small narrow-wide rows B3(row spacing 0.4+1.2 m))were designed to explore the effects of seedling density and row spacing on growth,nutrient content,light interception of P.tomentosa.Important findings:(1)The seedling height,root biomass and biomass of A2B3 were the highest,294.65 cm,151.92 g and 328.77 g,respectively.The leaf nitrogen concentration of A3B3 was the highest with a value of 16.43 g/kg.Wide-and-narrow row planting significantly increased the nitrogen concentration of stem and root,light interception and leaf area index(2)Light interception was significantly positively correlated with seedling height,root collar diameter,aboveground biomass,underground biomass and total biomass of P.tomentosa(P<0.05),and negatively correlated with stem/root(SR).Among them,light interception and biomass had the highest determinant coefficient,with R2 reaching 0.408.(3)The storage of non-structural carbohydrates in A3B2 and A3B3 of seedlings was ideal.The contents of non-structural carbohydrates in stems and roots of A3B2 were 55.51 mg/g and 121.24 mg/g.The highest contents of non-structural carbohydrates in stems and roots of A3B3 were 89.12 mg/g and 110.19 mg/g.There were significant differences in the content of non-structural carbohydrates in different organs of P.tomentosa.The order of proportion of soluble sugar in dry weight is root>leaf>stem;the proportion of starch in dry weight in organs is root>stem>leaf;and the propotion of non-structural carbohydrates in organs is root>stem>leaf.(4)One year after planting,the survival rate of P.tomentosa was positively correlated with seedling root collar diameter,underground biomass,root nitrogen concentration,and negatively correlated with SR.The correlation coefficient between survival rate of yong tree and nitrogen concentration of root at seedling stage was 0.60.The morphological index of young trees was significantly correlated with total seedling biomass,and the correlation coefficient between underground biomass of yong tree and total seedling biomass at seedling stage reached 0.72.Nitrogen concentration of stems and roots at outplangting stage was related to SR at seedling stage,and the correlation coefficient between the nitrogen concentration of stem and SR at seedling stage was 0.57.