干旱胁迫对杨树幼苗氮磷化学计量特征及分配格局的影响

Effects of drought stress on N and P stoichiometry and allocation of poplar seedlings

以1年生杨树幼苗为研究对象,采用盆栽控水法,设置适宜水分、轻度、中度和重度胁迫处理(即田间持水量的80%、60%、50%和40%),研究干旱胁迫对杨树幼苗不同器官氮磷化学计量的影响。结果表明:与适宜水分处理相比,随着干旱胁迫时间延长,叶N含量先降低后增加,茎N含量先下降后无显著差异,根N含量下降;叶和茎P含量先降低后升高,根P含量增加;叶和茎N/P先升高后降低,根N/P下降。根茎叶之间的N或P含量呈显著正相关(P<0.05),而各器官的N与P含量间均无显著相关性(P>0.05)。N含量和N/P在各器官顺序为叶>茎和根,P含量在各器官中无显著差异。各器官N含量和N/P变异系数为根>茎>叶;P含量变异系数在各器官相似。研究表明,随干旱胁迫加剧,杨树幼苗生长受N元素的限制作用增强;N在叶和茎中的变异程度小于P,而根中N和P的变异性相近。

To understand the effects of drought stress on N and P stoichiometry in different organs of poplar seedlings,one-year-old Populus × xiaozhuanica cv.Zhangwu seedlings were grown under suitable water level,mild,moderate and serious water stress treatments,i.e.,80%,60%,50% and 40% of field capacity,with water controlling method in pots.The results showed that compared with the suitable water level treatment,with the increase of drought stress time,N content firstly declined and then increased in leaves,while it firstly decreased and then had no difference with the suitable water treatment in stems,and declined in roots in the drought stress treatments.P content firstly decreased and then increased in leaves and stems,and increased in roots in the drought stress treatments.However,N/P firstly elevated and then declined in leaves and stems,and decreased in roots in drought stress treatments.There were significant correlations among roots,stems,and leaves in N or P content（P〈0.05）,while N content was not correlated with P content in all organs（P〉0.05）.N content of different organs followed the order：leavesstems and roots,but there was no significant difference in P content among different organs.Meanwhile,the coefficients of variation for N content and N/P followed the order：rootsstemsleaves,but the coefficient of variation for P content was similar in different organs.These results indicated that with the increase of drought stress,N limitation for poplar seedlings was enhanced.The variation degree of N was smaller than that of P in leaves and stems,but the variations of N and P were similar in roots under drought stress.