A Study On Fine Root Distribution Patterns Of Populus Tomentosa Under Agroforestry

Fine roots are the main organs for plants to absorb water and nutrients,they play an irreplaceable role in the growth and development of plants.Currently,most of the research on Populus tomentosa roots are focus on the distribution of root biomass and the relationship between the roots and soil resources.There are few studies on the spatial distribution of root system of young Populus tomentosa under agroforestry system.This study uses split-plot experiment design.The main factor is planting density with two treatments of 2m × 3m and 3m × 4m.The secondary factor is cropping patterns with three treatments of Populus tomentosa + Arachis hypogaea+ Spinacia oleracea,Populus tomentosa + Arachis hypogaea,Populus tomentosa.After two years of tree planting,the distribution characteristics and tendency of fine roots and tree growth aboveground for Populus tomentosa under different planting density and cropping patterns were studied.The results shows:(1)Planting density has a significant effect on the height of Populus tomentosa after two years of planting(P<0.05).The tree height was 6.41 m in the 2m × 3m planting density,which was significantly higher than 5.68 m in 3m × 4m density.(2)Fine root biomass density and surface area density reached the maximum value in the cropping patterns of Populus tomentosa + Arachis hypogaea,which significantly increased by 60.20% and 80.20% than that of the single populus tomentosa pattern.The specific fine root length of Populus tomentosa reached the maximum value of 2513.068 cm/g under the combination of 3m× 4m planting density and Populus tomentosa + Arachis hypogaea cropping patterns,which was significantly higher than that of the remaining five treatment combinations.(3)The fine root biomass density,fine root length density,specific fine root length,fine root surface area density in soil depth within 0 ? 40 cm under Populus tomentosa + Arachis hypogaea+ Spinacia oleracea,Populus tomentosa + Arachis hypogaea cropping patterns were less than that of the single Populus tomentosa.Oppositely,in soil depth within 40?80cm,those indicators of intercropping patterns were higher than single Populus tomentosa.It showed that the intercropping crops could cause the fine roots of Populus tomentosa moving downward.(4)In vertically,the fine root biomass density,fine root length density,fine root surface area density of Populus tomentosa reached the maximum value in soil depth within 0 ? 20 cm.In horizontally,the fine root biomass density,fine root length density,fine root surface area density of Populus tomentosa reached the maximum value within 0 ? 30 cm.There was a difference in the distribution trend of fine roots under planting density.In the 2m × 3m planting density,the fine root biomass density,fine root length density,fine root surface area density of Populus tomentosa showed a tendency of decreasing first and then increasing with horizontal distance increased from the tree.However,in the 3m × 4m planting density,the above mentioned root indexes decreased with horizontal distance increased from the tree.