Impact of water stress under ambient and elevated carbon dioxide across three temperature regimes on soybean canopy gas exchange and productivity.

Authors: SINGH, SHARDENDU - Oak Ridge Institute For Science And Education (ORISE); Reddy, Vangimalla; Mura, Jyostna; Timlin, Dennis

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2021
Publication Date: 8/13/2021
Citation: Singh, S., Reddy, V., Mura, J.D., Timlin, D.J. 2021. Impact of water stress under ambient and elevated carbon dioxide across three temperature regimes on soybean canopy gas exchange and productivity. Scientific Reports. 11:16511. https://doi.org/10.1038/s41598-021-96037-9.
DOI: https://doi.org/10.1038/s41598-021-96037-9

Interpretive Summary: Changes in climate conditions such as higher temperatures and frequent drought episodes cause severe crop yield losses. This study was aimed to understand the combined effects of rising CO2, warmer temperature, and drought stress on physiological, developmental, and yield responses in soybean. The impact of drought stress was detrimental and reduced soybean yield under ambient CO2 conditions than elevated atmospheric CO2. Moderate high-temperature stress improved photosynthesis, biomass, and seed yield under elevated CO2 compared to ambient CO2 in soybean. Our findings suggest that elevated atmospheric CO2 benefit soybean productivity, at least partially, under drought stress and moderately warmer temperature than ambient CO2 conditions. These findings should help researchers understand the interactive effects of abiotic stresses and improve crop yields to environmental stress conditions.

Technical Abstract: The agriculture cropping system is simultaneously exposed to multiple environmental factors. The current study investigated the concept that elevated CO2 will enhance soybean productivity under water stress and or suboptimal temperature. Soybean was grown outdoor in the sunlit, controlled environment Soil-Plant-Atmosphere-Research (SPAR) chambers under two-level of irrigation (WW, well water; WS, water stress that ˜35% of the total amount of WW) and CO2 (400 and 800 µmol mol-1, ambient, aCO2 and elevated, eCO2. respectively) and each at the three day/night temperature (T) regimes of 24/18 (moderately low, MLT), 28/22 (optimum, OT), and 32/26 (moderately high, MHT) °C. Results showed the greatest negative impact of WS on plant traits such as canopy photosynthesis (PCnet), total dry weight (TDwt), and seed yield. The decreases in these traits ranged between 40 and 70% averaged across temperature. However, the impact of WS was more detrimental in the aCO2 than in eCO2. The WS also reduced individual seed size adding to the loss of seed yield. The MHT had an increased PCnet, TDwt, and seed yield primarily under eCO2 with a greater increase under WW than WS conditions. The eCO2 stimulated PCnet, TDwt, and seed yield to a greater extent in WS than in the WW treatment. For instance, on average across T regimes, within an irrigation treatment, eCO2 stimulated around 25% and 90% dry mass under WW and WS, respectively, relative to aCO2. Despite the reduced canopy evapotranspiration and the total amount of seasonal water use under eCO2 and WS conditions, an increased water use efficiency was only found under eCO2. The MHT consistently showed greater water use and lower water use efficiency across CO2 and irrigation treatments. Thus, eCO2 appears to benefit soybean productivity, at least partially, under WS and the moderately warmer temperature of this study.