Effect of atmospheric turbidity on the photosynthetic rates of leaves

✍ Scribed by K.J. McCree; M.E. Keener

• Publisher: Elsevier Science
• Year: 1974
• Weight: 422 KB
• Volume: 13
• Category: Article
• ISSN: 0002-1571
• DOI: 10.1016/0002-1571(74)90075-2

✦ Synopsis

The special irradiance of sun, sky and sun + sky (global) radiation on a horizontal surface was measured on clear days of low and high atmospheric turbidity (Volz turbidity coefficient 0.02 to 0.28). The waveband covered was 300--740 nm. The sun component was greatly reduced by the increase in turbidity, especially in the U.V., but most of the losses were recovered in the sky component. There was a spectrally-neutral loss of less than 20% in the global irradiance of photosynthetically active radiation (quantum flux density in the waveband 400--700 nm). The spectral quantum yield of photosynthesis in the U.V. was shown to be strongly affected by absorption in the epidermis. The results of the spectral irradiance and spectral quantum yield measurements were combined in calculations, which showed that changes in epidermis absorption or in atmospheric turbidity are unlikely to affect the photosynthetic rates of field crops by more than 5%.