合理施肥是杨树苗木生产的重要管理措施。通过对杨树(NL80351)苗木配方施肥试验，研究不同N、P、K配方施肥对杨树苗木生长的影响，并对杨树苗木施肥的合理N、P、K配方进行回归分析。结果表明：配方施肥对杨树苗高、根系及各组织生物量均有显著的促进作用，其中，施用17 mg/L的N、10 mg/L的P及8.5 mg/L的K对根、皮、枝、叶生物量及总生物量增长的促进最显著，比对照分别增加294%、66%、96%、126%、118%。回归分析得出，促进苗高生长的适宜N、P、K质量浓度分别为13.03、3.76、2.24 mg/L，促进根系生长的适宜N、P、K质量浓度分别是2.36、2.12、4.71 mg/L。因此，可以得出,N素营养有利于杨树苗高增长，K的营养则对根系生长具有促进作用，苗木生长初期应在施用P、K肥料同时加强N素营养，促进苗高生长，生长后期应该控制N肥并加强P、K肥，以便苗木健壮，提高抗逆性和苗木品质。

As we all known, a wellplanned fertilization method plays a very important role in poplar seedling production. This paper focused on the question whether formulated fertilization is good for the the growth of poplar seedling and it explores the best one in final. In the relative experiment for this question, nine kinds of formulated fertilizer solutions mixed with N，P，K at different concentration ratio were used during the growing process of poplars named as Populus deltoids Bartr.cv.‘Lux’× P.deltoides Bartr.cv.‘Havard’. The results showed that the nine kinds are all favorable for poplar seedling growth and the third one with N，P，K at concentration ratio of respectively 17 mg/L, 10 mg/L and 8.5 mg/L, mostly increased the biomass for the root, bark, branch, leaf and all of them as a whole.Comparing with the control, they are increased by 294%, 66%, 96%, 126% and 118% respectively. According to the regression equation for the data obtained from the experiment above, the rational concentration of N，P，K for seedling’s growth of poplar was 1303 mg/L,3.76 mg/L and 2.24 mg/L respectively, while for the root growth that was 2.36 mg/L, 2.12 mg/L and 471 mg/L respectively. Therefore, the amount of fertilizer N should be increased in the early stage of growth when the fertilizer P and fertilizer K were being used, but in later stage of growth the amount of fertilizer N should be controlled properly and in turn the amount of fertilizer P and fertilizer K should be increased, which was favorable for improving stress resistance and equality of the poplar’s seedlings. So the formulated fertilization would promote the growth of seedling and root of poplar and increase the biomass production, in particular, N was good for growth of seedling height and tissue biomass, while as K was favorable for root growth.