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United States Department of Agriculture

Agricultural Research Service


item Baker, Neil
item Ort, Donald
item Harbinson, Jeremy
item Whitmarsh, Clifford

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 8/8/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The foundation for understanding light processing by leaves is a detailed understanding of how the chloroplast operate within, and interact with, the environment of leaf. To convert the transient energy of light into stable chemical energy, the photo synthetic apparatus performs a series of energy transforming reactions. The energy of absorbed light is converted to charge separations within each of the two photo systems. All subsequent reactions of photosynthesis leading to the production of ATP and NADPH and thereafter to the reduction of CO2, as well as lesser amounts of other inorganic molecules, is driven by the light energy captured by the photo systems. As irradiance on a leaf increases the relationship between photosynthesis and absorbed light transitions from linear to nonlinear and eventually reaches saturation where no further increases in photosynthesis accompany increased light absorption. Within the linear region of the light response, the quantum yields of CO2 assimilation operates within 15 percent of its theoretical maximum. This remarkable efficiency requires both that the distribution of absorbed light between the two photo systems is very closely balanced and that under these limiting light conditions nearly all ATP and NADPH production is used for CO2 assimilation.

Last Modified: 05/22/2017
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