臭氧胁迫对大豆氮磷化学计量特征的影响

Elevated Ozone Affects N and P Ecological Stoichiometry of Soybean

研究臭氧浓度升高对大豆(Glycine max)器官生态化学计量特征的影响,对预测未来生态过程和生物地球化学循环有重要作用。以大豆为试验材料,利用开顶室气室(OTCs)探讨臭氧胁迫对大豆不同器官氮磷化学计量特征的影响。试验设置3个处理:CK处理(对照,O3浓度为45 nmol·mol^(-1))、T1处理(O3浓度为(80±10) nmol·mol^(-1))、T2处理(O_3浓度为(110±10)nmol·mol^(-1))。结果表明,随着生育期的延长,大豆根系和茎秆N含量呈升高趋势,叶片N含量呈先升高后降低的趋势。与对照相比,臭氧浓度升高使根N含量在分枝期和结荚期显著升高(P<0.05),开花期T1处理下显著降低7.13%(P<0.05),T2处理下显著升高17.37%(P<0.05);茎N含量均显著升高,叶片N含量在开花期显著升高,结荚期显著降低。臭氧浓度升高使大豆根、茎、叶P含量表现出不同程度的增加趋势,仅有根系P含量在开花期T1处理下显著降低15.96%(P<0.05),叶片P含量分别在分枝期和结荚期T2处理下显著降低25.10%和11.37%(P<0.05)。茎和根P含量间呈显著正相关(P<0.05),根和茎中N和P含量之间呈显著正相关(P<0.05);N含量和N/P在各器官中表现为叶>根>茎;P含量在各器官中无显著差异。各器官N含量变异系数表现为茎>根>叶;P含量在各器官中变异系数相似;N/P变异系数表现为叶>根>茎。随着臭氧浓度升高和生育期的延长,大豆各器官N/P均小于14,说明大豆生长主要受N素限制。

Studying the effect of elevated ozone concentration on the ecological stoichiometry of soybean(Glycine max)organs plays an important role in predicting future ecological processes and biogeochemical cycles.Open-top chambers(OTCs)were utilized to study the effects on N(nitrogen)and P(phosphorus)stoichiometric characteristics in different organs of soybean under elevated O3 concentration [(80±10)nmol·mol.1 and(110±10)nmol·mol.1].The results showed that with the extension of growth period,the N content of soybean in roots and stems increased,while the N content in leaves increased firstly and then decreased under enhanced ozone.Compared with the control,elevated ozone resulted in a significant increase in root N content at branching and podding(P<0.05),but a significant decrease of 7.13%(P<0.05)for T1 treatment at flowering and a significant increase of 17.37%(P<0.05)for T2 treatment;N content in stems increased significantly both T1 and T2 treatment;N content in leaves increased at flowering and decreased significantly at podding.On the whole,P content in different organs increased under elevated ozone concentration,but P content in roots decreased significantly 15.96%(P<0.05)at flowering,P content of leaves decreased significantly 25.10% and 11.37%(P<0.05)for T2 treatment both branching and podding respectively.There were significant correlation in P content of root and stem(P<0.05),and N content was significantly correlated with P content in root and stem(P<0.05);N content and N/P ratio of different organs ranked in the order leaf>root>stem,but there was no significant difference in P content among different organs.Meanwhile,the coefficients of variation for N content ranked in the order stem>root>leaf,and the coefficients of variation for N/P ranked in the order root>leaf>stem,but the coefficient of variation for P content was similar in different organs.These results reveal that N/P ratio of soybean organs is less than 14 under ozone stress,indicating that soybean growth is mainly limited by N.