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United States Department of Agriculture

Agricultural Research Service

Research Project: Identifying and Manipulating Key Determinants of Photosynthetic Production and Partitioning

Location: Global Change and Photosynthesis Research

Title: The impact of modifying antenna size of photosystem II on canopy photosynthetic efficiency – development of a new canopy photosynthesis model scaling from metabolism to canopy level processes

item Song, Qingfeng
item Ort, Donald
item Zhu, Xinguang

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Canopy photosynthesis is the result of photosynthesis according in leaves from the top to the bottom of the canopy where light conditions are very different. Since canopy photosynthesis is highly predictive pf biomass production, considerable effort has been devoted to improving seasonal canopy photosynthesis. In a crop canopy, upper-layer leaves usually absorb much more light than photosynthesis is able to use and the excess light energy must be dissipated to avoid photo damage. At the same time, lower-layer leaves are usually limited by available light. Improving the distribution of light inside a canopy can increase light use efficiency and hence increase canopy photosynthesis. In this work, a canopy photosynthesis model was developed where the heterogeneity of light inside the canopy is considered. This model enables an accurate prediction of light environment of a canopy with user defined canopy architecture parameters.

Technical Abstract: Canopy photosynthesis describes photosynthesis of an entire crop field and positively correlates with biomass production. Much effort in crop breeding has focused on improving canopy architecture and hence light distribution inside the canopy. Here, we develop a new integrated canopy photosynthesis model including canopy architecture, a ray tracing algorithm and C3 photosynthetic metabolism to explore the option of manipulating leaf photosystem properties for greater canopy photosynthetic CO2 uptake rate (Ac) and nitrogen use efficiency (NUE). The results from model simulation show that (1) efficiency of photosystem II (PSII) increased when leaf chlorophyll concentration was decreased by decreasing antenna size and (2) the photosynthetic photon flux density of leaves at the bottom layers was increased when chlorophyll concentration was decreased. Furthermore, Ac was increased by around 3% and NUE was increased by about 14% when chlorophyll concentration was decreased to 40% by reducing antenna size of PSII only. However, if the leaf nitrogen saved by decreasing leaf chlorophyll concentration can be optimally allocated to other components of photosynthesis, both Ac and NUE can be increased by over 30%. Optimizing chlorophyll concentration can be used as a strategy in crop breeding for increasing biomass production and crop yields.

Last Modified: 09/18/2017
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