Effects Of Fertilization On Growth Of First Year Outplanting And Potted Seedlings For Male Populus Tomentosa

Populus tomentosa Carr.is an important afforestation tree in northern China.In recent years,catkins and other issues produced by female poplar plants have caused some environment problems,but the male poplar does not has such problem.In this study,we conducted an experiment about effects of fertility gradients and different nitrogen ratios on male Populus tomentosa stocks in the nursery of Yongning Town,Yanqing District,Beijing.Through the indexes of growth,nutrient content and tissue structure to find out the optimum fertilizer amount and appropriate nitrogen ratio of Populus tomentosa stocks at the first year outplanting.The result showed:The field trial result showed:(1)The effects of different fertilizers on the growth of Populus tomentosa 331 and Narrow Crown No.3 were different significantly and the growth indexes of Populus tomentosa 331 were better than that of Narrow Crowns No.3 in terms of biomass,stock height,root collar diameter and nutrient content at the fertilizer amount of 235g/tree.The growth indexes of narrow crown No.3 reached the maximum when applied high concentration of the garden waste composting(40%by volume of planting hole).(2)The changes of chlorophyll content in leaves of Populus tomentosa 331 and Narrow Crown No.3 were August>July>September,but there were differences between the two cultivars.Populus tomentosa 331 had the highest chlorophyll content at high concentration of organic fertilizer(1000g/plant)and low Concentration of compound fertilizer(235g/strain),while Narrow crown No.3 was more inclined to high concentration of organic fertilizer treatment(1000g/strain).The Potting test result showed:(1)The growth indexes of stock height,root collar diameter,biomass and fine root increased significantly with the increase of nitrate nitrogen ratio at the same nitrogen fertilization level.Populus tomentosa 331 tended to absorb high proportion of nitrate nitrogen.The tendency of Populus tomentosa 331 absording fertilizer:nitrate nitrogen>amide nitrogen>ammonium nitrate ratio fertilization>ammonium nitrogen.(2)The effect of ammonium nitrate was significantly higher than that of single nitrogen fertilizer in terms of stock nutrient content and leaf chlorophyll content for Populus tomentosa 331.When(NH4+--N):n(NO3--N)was 25:75,the nutrient content and chlorophyll content reached the highest,which indicated that the high proportion of ammonium nitrate was beneficial to nutrient accumulation.