Submitted to: Current Opinion in Plant Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/27/2012
Publication Date: 12/1/2012
Citation: Zhu, X., Song, Q., Ort, D.R. 2012. Elements of a dynamic systems model of canopy photosynthesis. Current Opinion in Plant Biology. 15(3):237-244. Interpretive Summary: An element of meeting the challenge of doubling the global food production will have to be increasing the efficiency of crop canopy photosynthesis. Crop yield is inherently related to the seasonal integral of net canopy photosynthesis. Canopy photosynthetic CO2 uptake is the integral of photosynthetic CO2 uptake from both sunlit and shaded leaves, the proportion of which changes diurnally throughout the growing season with the changing sun leaf angle. For a crop canopy containing several leaf layers, the CO2 uptake for canopies shows little sign saturation even at full sunlight. Because of this fact, photosynthetic CO2 uptake by shaded leaves can account for up to about 50% of the total. The historical misunderstanding of the relationship between photosynthesis and crop yields is largely due to considering leaf instead of full canopy photosynthesis to derive the relationship. In this article is developed the rationale for a systems-based canopy photosynthesis model that will enable studies to dramatically improve insight into engineering crops for improved canopy photosynthetic CO2 uptake, resource use efficiencies and yield.
Technical Abstract: Improving photosynthesis throughout the full canopy rather photosynthesis of only the top leaves of the canopy is central to improving crop yields. Many canopy photosynthesis models been developed from physiological and ecological perspectives, however most do not consider heterogeneities of microclimatic factors inside a canopy, canopy dynamics and associated energetics, or competition among different plants, and most models lack a direct linkage to molecular processes. Here we described the rationale, elements, and approaches necessary to build a dynamic systems model of canopy photosynthesis. A systems model should integrate metabolic processes including photosynthesis, respiration, nitrogen metabolism, resource re-mobilization and photosynthate partitioning with canopy level light, CO2, water vapor distributions and heat exchange processes. In so doing a systems-based canopy photosynthesis model will enable studies of molecular ecology and dramatically improve our insight into engineering crops for improved canopy photosynthetic CO2 uptake, resource use efficiencies and yield.