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This test Granville County, Hebei nursery field Populus tomentosa base ratio of fertilization experiment in the field , using L . (34 ) orthogonal experimental design and research of N , P , K ratio fertilization S86 clones of Populus tomentosa , BT17 diameter at breast height , tree height , volume growth , physiological characteristics , chlorophyll and nutrient elements content of the Chinese white poplar growth dynamic change and Populus tomentosa root diameter , leaf nutrient element content of the variation , in order to put forward a reasonable of Populus tomentosa different varieties best fertilization period , fertilizer type and amount of fertilizer , the establishment of fast growing timber of Populus tomentosa rational fertilization program provide a theoretical basis for the Chinese white poplar plantation to create , to further promote the rapid development of poplar industry . The results are as follows : ( 1 ) N fertilizer is the main fertilizer affect the growth of Chinese white poplar timber , followed by fertilizer P , K fertilizer , and the best ratio of fertilizer to promote the Populus tomentosa individual volume growth : varieties the S86 is N3P3K1 ( urea 650g / strain , superphosphate 1000 g / strain , potassium sulfate , 0 g / strain ) , species BT17 N3P2K1 ( and urea 650 g / strain , superphosphate 500g/strain , the Potassium Sulfate g / strain ) . (2) fertilization period should be selected the Populus tomentosa diameter at breast height , tree height , before the peak of the fast-growing , early May . If the second top-dressing , you should choose the diameter at breast height and tree height growth peak period before fertilization , dressing again time should be chosen July . ( 3 ) N , P , K fertilizer on the the Populus tomentosa net photosynthesis, transpiration , stomatal conductance of not significant ( P lt ; 0.05 ) , analysis of the impact of Populus poor value net photosynthesis , transpiration, stomatal conductance degrees fertilization factor size order : N fertilizer gt ; P fertilizer gt ; K fertilizer . And chlorophyll content in leaves of Populus tomentosa processing the P9 ( urea 650 g / strain , superphosphate 1000 g / strain, potassium sulfate 150 g / strain ) . (4) fertilization effect changes in the leaves of nitrogen, phosphorus , potassium content , promote the absorption of nitrogen , phosphorus and potassium . In leaf N and P content of basic monthly variation showed a single peak curve , little K content changes in the basic rate ; and Populus tomentosa organizations N , P element content in the order: leaf gt ; stem gt ; roots ; K elements the content in Populus tomentosa organizations in the accumulation of the order : leaf gt ; root gt ; stems.
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