NP配施对平茬后云南松苗木N、P、K化学计量比的影响

为了解NP配施对平茬后云南松（Pinus yunnanensis）苗木各器官N、P、K化学计量比的影响，分析云南松苗木不同器官（根、茎、叶、萌条）的ω（N）∶ω（P）、ω（N）∶ω（K）、ω（P）∶ω（K）化学计量比的季节变化特征，探讨各器官间N、P、K化学计量比的相关性及其变异来源。采用N、P二因素三水平的3×3回归设计开展不同施肥试验，并对苗木采样测定，研究NP配施对平茬后云南松根、叶、茎及其萌条N、P、K化学计量特征的影响。结果表明：平茬后云南松苗木不同器官的营养元素分配没有统一的规律，展现出丰富的变异。随着施肥季节的变化， ω（N）∶ω（P）在根、茎和萌条中逐渐下降，在叶中先下降后上升，但总体差异不大。单施N肥、P肥和NP配施均对云南松苗木生长的影响产生一定差异，总体来看NP配施更有利于促进苗木的生长，且以处理5（N₁P₁）表现为极显著（P<0.01）。云南松苗木各器官N、P、K化学计量比主要受N×P交互作用的影响，其次是N，影响最小的是P。除在根和叶中ω（N）∶ω（P）与ω（N）∶ω（K）之间相关性发生改变之外，其余两两间的正负相关性均保持不变，而 ω（N）∶ω（P）与ω（P）∶ω（K）、ω（N）∶ω（K）与ω（P）∶ω（K）的相关性均随着施肥季节的变化相关性发生改变，且相关系数降低，分别受P和K的调控。平茬改变植株体内的营养元素含量，不同施肥处理促使云南松各器官中N、P、K化学计量特征差异极显著（P<0.01）。NP配施可以有效缓解单施N肥、P肥对植株的限制作用，使养分处于一个平衡状态，从而满足植株对生长的需要。

Effects of Combined Application of N and P on Stoichiometric Ratio of N,P and K of Pinus yunnanensis Seedlings after Stumping

To understand the effects of combined application of N and P on the stoichiometric characteristics of N， P and K in different organs（root， stem， leaf and sprout） of Pinus yunnanensis seedlings， the seasonal variation characteristics of the stoichiometric ratio of ω（N）∶ω（P）， ω（N）∶ω（K） and ω（P）∶ω（K） in different organs（root， stem， leaf and sprout） of P. yunnanensis seedlings were analyzed， and the seedlings of P. yunnanensis treated with different N and P were sampled and measured， and different fertilization experiments were carried out by using 3×3 regression design with 2 factors and 3 levels of N and P. The effects of combined application of N and P on the stoichiometric ratio of N， P and K in roots， leaves， stems and sprouts of P. yunnanensis after stumping were studied. The results showed that P. yunnanensis seedlings had no rule for the distribution of nutrient elements in different organs after flat stubble， but showed rich variation. With the change of fertilization season， ω（N）∶ω（P） decreased gradually in roots， stems and sprouts， and decreased first and then increased in leaves， but the overall difference was not significant. There were some differences in the effects of single application of N， P and combined application of N and P on the growth of P. yunnanensis seedlings. In general， the combined application of N and P was more beneficial to promote the growth of seedlings， and treatment No.5（N₁P₁） showed extremely significant（P<0.01）. The N， P and K stoichiometric ratios of all organs of seedlings were mainly influenced by the N×P interaction， followed by N and P was the least. The positive and negative correlations between ω（N）∶ω（P） and ω（N）∶ω（K） remained unchanged except in roots and leaves were changed， where the correlation between ω（N）∶ω（P） and ω（N）∶ω（K）. The correlations between ω（N）∶ω（P） and ω（P）∶ω（K）， ω（N）∶ω（K） and ω（P）∶ω（K） changed with seasonal changes in fertilizer application and the correlation coefficients decreased， regulated by P and K， respectively. Stumping changed the content of nutrient elements in the plant， and different fertilization treatments made significant differences in the stoichiometric characteristics of N， P and K in different organs of P. yunnanensis （P<0.01）. The combined application of N and P could effectively alleviate the limiting effect of single application of N and P on plants， and the nutrients was in a balanced state， and meet the needs of plant growth.