Narrow waveband spectral reflectance, chlorophyll fluorescence and gas exchange measurements were made sequentially on individual leaves of <i>Vicia faba</i> at three levels of 500, 1000 and 1500 mmol m<sup>-2</sup> s<sup>-1</sup>. PRI was calculated from the reflectance data and correlated with LUE calculated from gas exchange and photosystem II( PS II) efficiency measured from chlorophyll fluorescence. PRI was linearly related to photosystematic LUE and PS II efficiency over the range of light levels and followed the diurnal light response of photosynthetic light-use-efficiency. The relationship between PRI and LUE was then investigated over boreal forests in Canada. Reflectance measurements of four stands were made from a helicopter-mounted spectroradiometer during the 1994 growing season. Eddy covariance towers were measuring CO<sub>2</sub> fluxes during this time and LUE was calculated from these data. A strong linear relationship was found between PRI and LUE for the four sites, and when expressed on a functional type basis of conifer and deciduous, the relationships were stronger still. The relationship between PRI and LUE at the canopy scale was further investigated in boreal forest in Siberia during the "green-up" period from winter into spring in 2000. During this time the photosystems were under stress as a result of extremes of temperature (from -20°C to +35°C) coupled with a high radiation load. Reflectance measurements of four stands were made from a helicopter-mounted spectroradiometer and PRI was calculated from these data. Eddy covariance towers were operating at each site and offered a means to calculate LUE. A significant linear relationship was apparent between PRI and LUE although the relationship was weaker than that found between PRI and LUE in the Canadian boreal forest. Collating the data for all the boreal forests highlighted a difference between the slopes of the PRI:LUE relationship. Reflectance measurements were also made from the eddy covariance tower of the Scots pine canopy and needles were sampled simultaneously for xanthophyll pigment determination. Strong linear relationships were observed between PRI, the epoxidation state of the xanthophyll cycle and LUE over the seasonal change and the diurnal cycle.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:659971 |
| Date | January 2000 |
| Creators | Nichol, Caroline Jane |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15517 |
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