Global climate models have indicated high probability of drought occurrences in the coming future decades due to the impacts of climate change caused by a mass release of CO_2. Thus, climate change regarding elevated ambient CO_2 and drought may consequently affect the growth of crops. In this study, plant physiology, soil carbon, and soil enzyme activities were measured to investigate the impacts of elevated CO_2 and drought stress on a Stagnic Anthrosol planted with soybean(Glycine max). Treatments of two CO_2 levels, three soil moisture levels, and two soil cover types were established. The results indicated that elevated CO_2 and drought stress significantly affected plant physiology. The inhibition of plant physiology by drought stress was mediated via prompted photosynthesis and water use efficiency under elevated CO_2 conditions. Elevated CO_2 resulted in a longer retention time of dissolved organic carbon(DOC) in soil, probably by improving the soil water effectiveness for organic decomposition and mineralization. Drought stress significantly decreased C:N ratio and microbial biomass carbon(MBC), but the interactive effects of drought stress and CO_2 on them were not significant. Elevated CO_2 induced an increase in invertase and catalase activities through stimulated plant root exudation.These results suggested that drought stress had significant negative impacts on plant physiology, soil carbon, and soil enzyme activities,whereas elevated CO_2 and plant physiological feedbacks indirectly ameliorated these impacts.
WANG YuhuiYAN DenghuaWANG JunfengDING YiSONG Xinshan
