Seeing the light from a different angle: creating new tools tom manipulate light environments and testing the effects on plant carbon and water fluxes

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Carter Berry, Biology, Wake Forest University, Winston-Salem, NC, Kendra Ellertson, Chapman University, Orange, CA and Gregory R Goldsmith, Biological Sciences, Chapman University, Orange, CA

Background/Question/Methods
For plants, not all light is equal. In addition to quantity and spectral quality, we now understand that the angle of light hitting the leaf surface (i.e. diffuse light independent of quantity or spectral quality) can significantly alter the carbon exchange of plants. The associated responses to diffuse light can be very large, altering photosynthetic rates by up to 50%. In short, this is an axis of variation in carbon fluxes that is poorly understood and has implications for the fundamental understanding of plant physiology and modeling of ecosystem carbon cycling. There are two aspects limiting our ability to incorporate angular quality into these frameworks: (1) the mechanism by which diffuse light alters carbon and water exchange and (2) an inability for current gas exchange systems to manipulate the angle of light.
Results/Conclusions
We synthesize results from multiple research projects that (1) demonstrates the mechanistic process that leads to changes in photosynthesis, transpiration, and stomatal conductance in diffuse light and (2) demonstrate a way to manipulate the angular quality of light in leaf level gas exchange. We demonstrate that diffuse light carbon exchange increases due to leaf structure that leads to greater light penetration and opening of stomata when the light environment is altered. There was no change to leaf biochemical efficiency. These results will now be coupled with stomatal conductance routines in ecosystem models to examine the effects on predictions of ecosystem fluxes. Due to the dearth of studies that control for angular quality, we have also created a new tool that interfaces with gas exchange systems that will allow for researchers to change the angular quality of light in their measurements. Any interested research groups should contact us to discuss options. We hope that these results combined with our new tool will drive the expansion of research quantifying and modeling the role that angular quality of light has on plant function and ecosystem fluxes.