不同种源五角枫幼苗叶片N、P化学计量学特征对氮添加的响应

不同土壤氮环境下植物对氮沉降的响应趋势不同,因此研究不同种源地的五角枫(Acer mono)对氮沉降的响应机理具有重要的意义。为了深入了解不同种源五角枫对氮沉降的适应和响应机制,主要通过3个种源的五角枫幼苗氮添加控制实验,分析不同种源的五角枫幼苗比叶面积(SLA)和叶片干物质含量(LMDC)以及叶片N、P含量和N∶P对氮添加的响应规律。结果表明:(1)不同氮添加处理下,内蒙古种源五角枫幼苗(NW)和山西种源五角枫幼苗(SW)的LDMC均显著低于对照,NW和SW在N4条件下表现为显著的促进作用。随着氮添加浓度的增加,NW与北京种源的五角枫幼苗(BW)的SLA在N4条件下显著增加;SW的SLA在N2的水平下显著增加。(2)氮添加下,只有SW的P_(mass)在N1水平下显著增加,N_(mass)在N1和N3水平下表现为显著增加。说明在低氮水平下,能够促进SW对P的吸收,从而增加植物体内对P的积累。同时在低氮和中高氮条件下,能够促进SW对N的吸收,说明SW能较好的适应低氮和高氮环境,使其生存能力更强。(3)分析变异来源及各指标的相关性得出,氮添加条件下,五角枫的SLA、LDMC、P_(area)及N∶P与氮添加处理呈显著的相关关系,而SLA、LDMC、N_(mass)、P_(mass)、Narea、P_(area)和N∶P对氮添加处理和种源的交互作用均未表现出相关关系,说明引起五角枫各性状主要受氮添加处理影响。(4)综合各指标的变化,氮添加条件下,NW的LDMC显著降低,SLA显著增大,同时叶N含量、叶P含量以及N∶P比较高;SW的LDMC显著降低,SLA增大,同时叶N含量、叶P含量表现为显著增大,结合叶经济谱理论分析得出,SW和NW属于"快速投资-收益"型,而BW倾向于"缓慢投资-收益"型。因此,不同种源的五角枫对于氮沉降的响应存在差异,并且持续的氮添加已经改变了五角枫的适应性。

Effect of nitrogen addition on leaf nitrogen and phosphorus stoichiometric characteristics of different provenance Acer mono seedlings

Plants growing in soils with different nitrogen levels under nitrogen deposition, therefore, the study of different provenances of Acer mono play an important role in understanding the response mechanism of nitrogen deposition. In this study, to understand the adaptation and response mechanisms of different provenances of A. mono under nitrogen deposition, nitrogen addition control experiments were conducted on three provenances of A. mono seedlings.The specific leaf area (SLA),leaf dry matter content (LDMC), leaf N content, P content and the N:P response to nitrogen addition in A. mono seedlings were analyzed. The results showed that (1) under different nitrogen addition treatments, the LDMC of A. mono seedlings from Inner Mongolia provenances (NW) and Shanxi provenances (SW) were significantly lower than those of CK, the LDMC of NW and SW increased significantly under the N4 condition. With an increase in nitrogen concentration, the SLA of A. mono seedlings of NW and Beijing provenances (BW) increased significantly under N4;while that of SW increased significantly at the N2 level. (2) With nitrogen addition, only the P_mass of SW increased significantly at the N1 level, and the N_mass showed a significant increase at the N1 and N3 levels. This indicated that under low nitrogen levels, SW can promote the absorption of P, thus, increasing the accumulation of P in plants. At the same time, under low, medium, and high nitrogen conditions, it can promote the absorption of SW to N, which shows that SW can better adapt to the low and high nitrogen environments, and improve its survival ability. (3) Analysis of the variation source and the correlation of each index, under nitrogen addition, revealed that the SLA, LDMC, P_area, and N:P of A. mono were significantly related to nitrogen addition. SLA, LDMC, N_mass, P_mass, N_area, P_area, and N:P showed no correlation between nitrogen addition treatment and provenance interaction; the results showed that the characteristics of A. mono were mainly affected by nitrogen addition. (4) Comprehensive changes of all indicators were shown; under nitrogen addition, the LDMC of NW decreased significantly, and the SLA increased significantly. Furthermore, the N and P contents in the leaves, and the N:P were higher; the LDMC of SW decreased significantly, SLA increased, and leaf N and P content increased significantly. According to the theory of leaf economic spectrum, SW and NW belong to the "quick-investment-income" type, while BW tends to follow the "slow-investment-income" type. Therefore, the different provenances of A. mono show variable responses under condition of nitrogen addition; continuous nitrogen addition affects the internal stability of A. mono.