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Reflexion and absorption of solar radiation by flowering canopies of oil-seed rape (Brassica napus L.)

Published online by Cambridge University Press:  27 March 2009

D. J. Yates  and
M. D. Steven
D. J. Yates
Affiliation:
Department of Physiology and Environmental Science, University of Nottingham School of Agriculture, Sutton Bonington, Loughborough, Leicestershire
M. D. Steven
Affiliation:
Department of Physiology and Environmental Science, University of Nottingham School of Agriculture, Sutton Bonington, Loughborough, Leicestershire
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Summary

Flowers were present over a period of approximately 6 weeks in 12 varieties of oil-seed rape. A linear relationship was found between flower cover (maximum 74%) and photon reflectivity (400–700 nm) which increased from around 0·047 during vegetative growth to 0·195 for a canopy in full flower. Reflexion and absorption of photons by flowers reduced light available to the leaf canopy and immature pods. Spectral measurements indicate that flowering canopies reflect substantially more radiation and absorb less than vegetative canopies between 500 and 700 nm but reflect less and absorb slightly more between 400 and 500 nm.

Seed yield was not strongly correlated with estimates of the radiation absorbed by the leaf canopy under the flower layer. It appears that whilst increased flower density in a canopy might be expected to contribute to increased seed yield, increased reflectivity by petals may have a negative effect on yield. Breeding for reduced petal size or for apetalous lines may result in improved yields by producing more efficient light distribution within the canopy.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 109 , Issue 3 , December 1987 , pp. 495 - 502
Copyright
Copyright © Cambridge University Press 1987

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