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Title
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The importance of the ratio uv-b/photosynthetic active radiation (par) during leaf development as determining factor of plant-sensitivity to increased uv-b irradiance - effects on growth, gas-exchange and pigmentation of bean-plants (phaseolus-vulgaris cv label)
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Author
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Abstract
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| To evaluate the effect of different naturally occurring irradiation conditions on the sensitivity of bean (Phaseolus vulgaris cv. Label) to increased UV-B levels, plants were grown under six different light treatments. In the control series (at ambient levels of UV-B), UV-B and visible light were decreased in parallel, resulting in three different total irradiation treatments with the same UV-B/PAR ratio. A second series with a 15% increase in UV-B irradiation at each PAR level was used to investigate the effect of UV-B under the varying total irradiance levels. The different total irradiance levels resulted in large differences in total dry weight, specific leaf weight, photosynthesis-light response and pigment concentrations. Nevertheless, the 15% increase in UV-B resulted in equal reductions in total dry weight (from 24.5 to 34.3%) and effective photosynthesis for all light levels. The accumulation of protective pigments in the primary bean leaves was strongly correlated to the total irradiance level (200% increase from the lowest to the highest light level), but was not influenced by increasing UV-B levels. As the UV-B/PAR ratio outside increases with decreasing total irradiance (when induced by cloud cover) this implies that low radiation levels are potentially dangerous to some plants, even though the UV-B levels may seem negligible. |
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Language
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English
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Source (journal)
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Plant, cell and environment. - Oxford, 1978, currens
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Publication
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Oxford
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Blackwell
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1994
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ISSN
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0140-7791
[print]
1365-3040
[online]
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DOI
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10.1111/J.1365-3040.1994.TB00295.X
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Volume/pages
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17
:3
, p. 295-301
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ISI
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A1994MY81900007
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Full text (Publisher's DOI)
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