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Modelling the effect of diffuse light on canopy photosynthesis in controlled environmentsA layered canopy model was used to analyze the effects of diffuse light on canopy gross photosynthesis in controlled environment plant growth chambers, where, in contrast to the field, highly diffuse light can occur at high irradiance. The model suggests that high diffuse light fractions (approximately 0.7) and irradiance (1400 micromoles m-2 s-1) may enhance crop life-cycle canopy gross photosynthesis for hydroponic wheat by about 20% compared to direct light at the same irradiance. Our simulations suggest that high accuracy is not needed in specifying diffuse light fractions in chambers between approximately 0.7 and 1, because simulated photosynthesis for closed canopies plateau in this range. We also examined the effect of leaf angle distribution on canopy photosynthesis under growth chamber conditions, as these distributions determine canopy extinction coefficients for direct and diffuse light. We show that the spherical leaf angle distribution is not suitable for modeling photosynthesis of planophile canopies (e.g., soybean and peanut) in growth chambers. Also, the absorption of the light reflected from the surface below the canopy should generally be included in model simulations, as the corresponding albedo values in the photosynthetically active range may be quite high in growth chambers (e.g., approximately 0.5). In addition to the modeling implications, our results suggest that diffuse light conditions should be considered when drawing conclusions from experiments in controlled environments.
Document ID
20040087583
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Cavazzoni, James
(The State University of New Jersey New Brunswick, NJ 08901-8500, United States)
Volk, Tyler
Tubiello, Francesco
Monje, Oscar
Janes, H. W.
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Acta horticulturae
Volume: 593
ISSN: 0567-7572
Subject Category
Man/System Technology And Life Support
Funding Number(s)
CONTRACT_GRANT: NAGW-5003
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Life Support Systems

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