Abstract Detail

The impact of climate change on plant physiology in natural and agricultural systems

Bernacchi, Carl [1], Ruiz-Vera, Ursula [2], Siebers, Matthew [3], Ort, Donald [2].

Disentangling the effects of short and long term warming events on crop physiology.

Ecosystems are facing threats from global atmospheric and environmental change. Agricultural ecosystems face these threats despite increasing dependency on agricultural products for food and fuel. Increasing atmospheric CO2 concentrations have been linked to higher yields, improved water use efficiency, and crop resilience to drought. However, considerable uncertainty exists when interactive effects are considered, for example the concomitant warming expected with rising CO2. The Soybean Free Air CO2 Enrichment (SoyFACE) facility is an experiment designed to investigate the effects of elevated CO2 concentrations on soybean (Glycine max) grown under field conditions. Results from SoyFACE show that, consistent with many other crop FACE experiments, CO2 increases photosynthesis rates for soybean, a C3 crop. Rising CO2 also lowers stomatal conductance, which is shown to reduce ecosystem water use via evapotranspiration by ca 10%. The increase in CO2 that is responsible for these effects is also the main driver for global warming, with both rising CO2 and warmer temperatures already occurring over the last few decades and will continue well into the future. The impact of changing growth temperature on crop physiology is complex given that temperature can dramatically impact all facets of plant metabolism as well as directly impact canopy microclimatic conditions. Research will be presented that attempts to disentangle the impact of rising temperature and increasing CO2 on physiology of maize and soybean. Because of the highly variable nature of temperature fluctuations, the research, which incorporates infrared heating arrays (T-FACE) on field-grown plants, includes both “global warming” treatments where temperature is increased throughout entire growing seasons as well as “climate extremes” where short-duration and high-intensity artificial heatwaves are imposed. Results from this research show a strong resilience of vegetative growth stages but significant sensitivity of reproductive growth stages to heat waves. Furthermore, combined season-long increases in temperature and CO2 results in a highly variable response of growth and physiology that is strongly dependent on background climatic conditions. Specific strategies have been identified to increase food production by conferring resilience of crops to increasing temperatures while potentially maximizing the beneficial aspects of growth associated with rising CO2. Specifically, experiments have been conducted on plants modified to (1) have more thermotolerant Rubisco Activase, (2) have more efficient photorespiratory carbon metabolism, and (3) overexpress limiting Calvin cycle enzymes. Results show that genetic improvements of crops under current growth conditions generally lead to even higher productivity when grown under increased temperatures. Novel strategies to further improve photosynthetic efficiency of crops are continually being investigated at SoyFACE to assess their potential to withstand the rapid changes occurring in nature.

1 - USDA-ARS, Global Change and Photosynthesis Research Unit, 1201 W. Gregory Drive, 196 E.R. Madigan Laboratory, Urbana, IL, 61801, USA
2 - University of Illinois, Carl R Woese Institute for Genomic Biology, 1206 W. Gregory Drive, Urbana, IL, 61801, USA
3 - USDA, Global Change and Photosynthesis Research Unit, 1201 W. Gregory Drive, Urbana, IL, 61801, USA

Short-term warming
Global change.

Presentation Type: Colloquium Presentations
Number: C1002
Abstract ID:682
Candidate for Awards:None

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