自然干旱下彰武小钻杨幼苗生态化学计量变化规律

Variation in ecological stoichiometry of Populus×xiaozhuanica cv.Zhangwu seedlings under natural drought

为了解干旱胁迫下彰武小钻杨(Populus×xiaozhuanica W.Y.Hsu et L.cv.Zhangwu)幼苗不同元素的变化规律及计量比特征,本研究通过盆栽实验,测定自然干旱0、6、12、18和24天幼苗各器官(叶、茎和根)中碳(C)、氮(N)、磷(P)和钾(K)含量,分析不同器官间各元素的相关性。结果表明:与干旱0天相比,干旱第6天,各器官N和K含量及C∶P和N∶P降低,P含量及C∶N和C∶K增加;干旱持续6~12天,各器官N含量及C∶P和N∶P增加,P含量下降;干旱持续12~24天,根C含量及C∶N、C∶P和C∶K呈下降趋势;持续干旱下幼苗叶、茎、根间的N和P含量、叶与茎间C含量及叶与根间K含量呈显著正相关;自然干旱过程中,彰武小钻杨幼苗会调整各器官C、N、P、K化学计量适应逐渐加剧的干旱胁迫,首先根系C供给增加、茎中K向叶和根转移,各器官N含量提升以抵御干旱胁迫,最后根系C供应减少,N消耗增加,P和K在体内积累。

To understand the variations of nutrients and stoichiometric ratios in Populus×xiaozhuanica cv.Zhang⁃wu seedlings under drought stress,we grew the seedlings in pots under a condition of continuous natural drought.Carbon(C),nitrogen(N),phosphorus(P),and potassium(K)contents in different organs(leaf,stem,root)were measured at 0,6,12,18 and 24 days after drought,and the correlations of elements among organs were analyzed.Results showed that N and K contents and C∶P and N∶P decreased but P content and C∶N and C∶K increased in all organs after 6 days of the drought.N content and C∶P and N∶P increased but P content decreased in all organs when the drought lasted from the 6th day to the 12th day.Root C content,C∶N,C∶P and C∶K showed downward trends when the drought lasted from the 12th day to the 24th day.Under continuous drought treatment,there were significant positive correlations in N or P content among leaves,stems,and roots,as well as C content between leaves and stems,and K content between leaves and roots.P.×xiaozhuanica cv.Zhangwu seedlings could adjust the stoichiometry of C,N,P,and K in various organs to adapt to the gradually intensified drought stress.First,C supply for roots increased,K transferred from stems to leaves and roots,and N content in each organ increased to resist drought stress.Finally,C supply for roots decreased,N consumption increased,and P and K accumulated in the seedlings.