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The combined effects of CO 2 concentration and solar UV‐B radiation on faba bean grown in open‐top chambers
Author(s) -
VISSER A. J.,
TOSSERAMS M.,
GROEN M. W.,
MAGENDANS G. W. H.,
ROZEMA J.
Publication year - 1997
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.1997.d01-64.x
Subject(s) - photosynthesis , biomass (ecology) , horticulture , acclimatization , irradiation , chemistry , botany , irradiance , shoot , ultraviolet b radiation , radiation , biology , ultraviolet radiation , agronomy , radiochemistry , physics , quantum mechanics , nuclear physics
The response of faba bean seedlings to the combined effects of increased atmospheric CO 2 concentrations ([CO 2 ]) and solar UV‐B irradiance was studied using open‐top chambers transparent to UV‐B radiation. The purpose of the study was to determine whether effects of increased [CO 2 ] on growth and physiology are modified by the present solar UV‐B fluence rate in the Netherlands. Seedlings were exposed to 350 or 700 μmol mol −1 CO 2. At both [CO 2 ], solar UV‐B irradiance was either present or reduced using polyester foil opaque to UV‐B radiation. To obtain information on the time dependence of increased [CO 2 ] and UV‐B radiation effects, three harvests were performed during the experiment. CO 2 enrichment resulted in increased biomass production at all harvests. At the final harvest, UV‐B radiation did not affect biomass production but a significant decrease was observed after 14 d of treatment. A reduction of the UV‐B fluence increased shoot length at both [CO 2 ] throughout the experiment. UV‐B radiation slightly altered biomass allocation. Plants grown at reduced levels of UV‐B radiation invested less biomass in flowers and more in stem material compared to plants grown at ambient UV‐B levels. CO 2 enrichment resulted in a stimulation of net photosynthesis after 26 and 38 d of treatment. UV‐B reduction did not alter this response. After 26 d of treatment, photosynthetic acclimation to CO 2 enrichment was observed, which was probably the result of accumulation of carbohydrates in the leaves. After 38 d, photosynthetic acclimation was no longer present. The UV absorbance of methanolic leaf extracts was increased by CO 2 enrichment only. Both CO 2 enrichment and solar UV‐B reduced the transmittance of radiation through intact attached leaves. Interaction between [CO 2 ] and UV‐B radiation was limited to UV‐A transmittance of leaves. Under prevalent experimental conditions, UV‐B radiation did not affect the measured physiological parameters. Most open‐top chambers used for climate change research are constructed of materials which do not transmit UV‐B radiation. Our results indicate that part of the ‘chamber effects’ on plant height often described in the literature might be explained by the absence of solar UV‐B radiation in these chambers.