中文摘要：

近年来大气N沉降日趋严重，导致森林土壤有效N含量增加，N／P发生改变，将会影响低P胁迫下林木的生长发育和P效率．本文以马尾松家系为研究对象，设置模拟N沉降与同质低P（介质表层与深层均缺P）、异质低P（介质表层P丰富、深层缺P）耦合的盆栽试验，研究N沉降对马尾松生长性状以及P吸收和利用效率的影响．结果表明：同质低P下，模拟N沉降对马尾松生长性状和P效率影响较小，但存在显著的N×家系互作效应，家系40×44和71×20在N沉降后生物量增加，家系36x29和73s23生物量降低；异质低P下，模拟N沉降显著增加了马尾松苗高、生物量以及P吸收效率等，其原因是促进了根系生长和表层土壤中根系分布比例的增加．不同P环境下模拟N沉降对马尾松生长的影响，还与植株NIP有关．同质低P环境下，马尾松植株NIP为13.8，植株对N敏感性低，酸性磷酸酶活性增加，但未改善马尾松生长状况．在异质低P环境中，植株N／P为9.7，模拟N沉降显著增加了苗木生物量和P吸收效率，但未显著改变酸性磷酸酶活性．

英文摘要：

Atmospheric nitrogen （N） deposition dramatically raised in recent decades, resulting in increases of soil N availability and N/P ratio, which would impact plant growth and P efficiency un der low P stress. Taking breeding population of Pinus massoniana as test materials, a pot experi ment was conducted to simulate two P conditions, i. e. , homogeneous low P availability vs. hetero geneous low P among soil layers, in combination with two N deposition levels on growth traits and P absorption and utilization efficiency of P. massoniana. Under the homogeneous low phosphorus con dition, growth traits and P efficiency of P. massoniana were not significantly improved by simulated nitrogen deposition, but significant nitrogen x family interaction effect was detected, with the bio mass of family 40×44 and 71×20 being increased, 36 x29 and 73 x23 being decreased. Under the heterogeneous low P condition, significant N effects on the seedling height, biomass and P absorp tion efficiency were observed, due to promoted root length and root distribution ratio of topsoil. In addition, the effects of simulated N deposition on growth and P efficiency of P. massoniana were relevant to the N/P ratio. Under the homogeneous low P condition, the N/P ratio of P. massoniana plant was 13.8, plants exhibited a low sensitivity to simulated N deposition, root secreted APase activity was increased but the plant growth was not promoted. In comparison, the plant N/P ratio was 9.7 under the heterogeneous low P condition, and the plant growth and P efficiency were signif icantly promoted, while no obvious change occurred in root secreted APase activity.