Interactions between rising CO2 and temperature drive accelerated flowering in model plants under changing conditions of the last century
Past studies have shown that flowering times have accelerated over the last century. These responses are often attributed to rising temperature, although short-term field experiments with warming treatments have under-estimated accelerations in flowering time that have been observed in long-term field surveys. Thus, there appears to be a missing factor(s) for explaining accelerated flowering over the last century. Rising atmospheric CO2 concentration ([CO2]) is a possible candidate, and its contributions to affecting flowering time over historic periods are not well understood. This is likely because rising [CO2] is confounded with temperature in the field and preindustrial [CO2] studies are relatively rare. To address this, we tested the individual and interactive effects of rising [CO2] and temperature between preindustrial and modern periods on flowering time in the model system, Arabidopsis thaliana. We used a variety of genotypes originating from diverse locations, allowing us to test intraspecific responses to last-century climate change. We found that accelerated flowering time between the full-preindustrial and full-modern treatments was mainly driven by an interaction between rising [CO2] and temperature, rather than through the individual effects of either factor in isolation. Furthermore, accelerated flowering time was driven by enhanced plant growth rates and not through changes in plant size at flowering. Thus, the interaction between rising [CO2] and temperature may be key for explaining large accelerations in flowering times that have been observed over the last century and that could not be explained by rising temperature alone.
KeywordsClimate change CO2 by temperature interaction Flowering time Global change Low CO2 Past conditions Phenology Plant development Preindustrial
We thank Courtney Bone, Ellen Duffy, Taylor Leibbrandt, Rebecca Orozco, Cedric Clark, and Diondré Jones-Sanders for their technical assistance in completing this project. This work was supported by National Science Foundation GK-12 and IGERT fellowships to SMW as well as National Science Foundation CAREER and NSF IOS awards to JKW. All raw data are available from the corresponding author upon request. JKW would like to thank Distinguished Professor James Ehleringer for his many contributions to science, the amazing training and mentoring that he provided her, and for his wonderful friendship and support over the years. She would also like to thank Edna Ehleringer for her encouragement, support, and friendship during her post-doctoral years and beyond.
Author contribution statement
SMW and JKW conceived and designed the experiments, performed the experiments, analyzed the data, and wrote the manuscript.
Funding was provided by the U.S. National Science Foundation (IOS) and the University of Kansas.
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflicts of interest.
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