Elevated CO2 reduces the adverse effects of drought stress on a high-yielding soybean (Glycine max (L.) Merr.) cultivar by increasing water use efficiency

Abstract

Soybean (Glycine max (L.) Merr.) is the world's most important grain legume. The impacts of climate change such as elevated CO2 and drought on soybean physiological and morphological responses are not well understood. This study evaluated the effects of elevated CO2 (ambient concentration + 200 mmol mol−1) and drought stress (35–45% of relative water content) on soybean leaf photosynthesis, chlorophyll fluorescence, stress physiological indexes, morphological parameters, biomass and yield over 2 years at the open-top chamber (OTC) experimental facility in North China. We found that drought decreased intrinsic efficiency of PSII (Fv’/Fm’), effective quantum yield of PSII photochemistry (ΦPSII..