Response of C, N and P Ecological Stoichiometry in Plants and Soils During a Soybean Growth Season to O3 Stress and Straw Return in Northeast China

Abstract

AimsC, N and P ecological stoichiometry plays important roles on biogeochemical cycles in ecosystems, yet the relationship between plant and soil stoichiometry and stoichiometric effects on the growth of soybean root in response to the O3 stress and straw return remain poorly understood. MethodsHere, a pot experiment was conducted in open top chambers to monitor the response of C, N and P ecological stoichiometry of leaves, shoots, roots and soils during a growing season (branching, flowering and podding stages) of soybean (Glycine max; a highly sensitive species to O3) to background O3 concentration (45 ± 10 ppb), O3 stress (80 ±10 ppb) and straw treatment (no straw return and straw return). ResultsThe O3 stress significantly decreased root biomass. The straw return significantly increased root biomass under the O3 stress at branching and flowering stages. Generally, the O3 stress and straw return showed significant effects on the C, N, P concentrations of leaves and soils, and stoichiometric ratios of leaves, shoots and microbial biomass. C, N, P concentrations and stoichiometric ratios of leaves, shoots, roots and soils responses to the O3 stress and straw return at branching stage were inconsistent with changes observed at the flowering and podding stages. The P conversion efficiency showed significant relationship with root P concentration under the combined effects of O3 stress and straw return. ConclusionsC, N, and P concentrations of soybean might be more important than stoichiometric ratios as a driver of defense against the O3 stress in the case of straw return.