Using Video to Understand Leaf Transpiration

Aaron Luttman, Bethany Lutheran College

In order to engage in photosynthesis, plant leaves absorb carbon dioxide through the opening of pores in their surfaces called "stomata." Water evaporates through open stomata, however, which is bad for the plant. Thus a plant tries to adjust its stomata so that it balances its need take in CO2 with its aversion to losing H2O. In order to visualize the extent to which these pores are open, we can use an infrared camera to measure fluorescence that corresponds to how much CO2 is being absorbed. In these pictures of the leaf, bright regions correspond to areas in which the stomata are closed and dark regions to areas in which the stomata are open. Pictures are continually recorded as these patterns change with time, and the result is a "movie" that must be processed mathematically in order to analyze the bright and dark regions. We use partial differential equations and very large computers to figure out how the bright regions change over time, and this information tells us (hopefully!) how the leaf decides when to adjust its stomata. If we can figure out how the leaf makes this decision, then we can get better insight into the biological process involved, which is not currently understood in its entirety. Results for an actual leaf and basic analysis of the patterns will be presented.