|KOEHLER, IRIS - Oak Ridge Institute For Science And Education (ORISE)|
Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2018
Publication Date: 3/1/2019
Citation: Koehler, I.H., Huber, S.C., Baxter, I.R., Bernacchi, C.J. 2019. Increased temperatures may safeguard the nutritional quality of crops under future elevated CO2 concentrations. Plant Journal. 97(5):872-886. https://doi.org/10.1111/tpj.14166.
Interpretive Summary: Soybean seeds are valued for their protein and oil content and micronutrients such as iron, zinc and selenium. It has been reported that when soybeans are grown at elevated CO2 (as will occur in the future), the concentrations of seed minerals are substantially reduced. This could exacerbate the mineral deficiencies that already constitute a global health problem. However, future climates will not only involve elevated atmospheric CO2 concentration but also increased temperatures, but the combined effect of these two environmental parameters on soybean seed composition has not been investigated. Our soybean studies suggest that the potential threat to human nutrition by increasing CO2 concentration may not be realized when plants grow at eCO2 and higher temperature that mimic future climate conditions. In addition, the results suggest a trade-off between optimizing yields for global change and seed nutritional quality, especially in the case of seed iron concentration.
Technical Abstract: Iron (Fe) and zinc (Zn) deficiencies are a global human health problem that may worsen by growth of crops at elevated atmospheric CO2 concentration (eCO2). However, climate change will also involve higher temperature, but it is unclear how the combined effect of eCO2 and higher temperature will affect the nutritional quality of food crops. To begin to address this question, we grew soybean (Glycine max) in a Temperature by Free-Air CO2 Enrichment (T-FACE) experiment in 2014 and 2015 under ambient (400 µmol mol-1) and elevated (600 µmol mol-1) CO2 concentration and under ambient and elevated temperatures (+2.7 °C day and +3.4 °C at night). In our study, eCO2 significantly decreased Fe concentration in soybean seeds in both seasons (-8.7% and -7.7%) and Zn concentration in one season (-8.9%) while higher temperature (at ambient CO2 concentration) had the opposite effect. The combination of eCO2 with elevated temperature generally restored seed Fe and Zn concentrations to levels obtained under ambient CO2 and temperature conditions, suggesting that the potential threat to human nutrition by increasing CO2 concentration may not be realized. In general, seed Fe concentration was negatively correlated with yield suggesting inherent limitations to increasing seed Fe. In addition, we confirm our previous report that the concentration of seed storage products and several minerals varies with node position at which the seeds developed. Overall, these results demonstrate the complexity of predicting climate change effects on food security when various environmental parameters change in an interactive manner.