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1999 (1)
1994 (1)
1Author    StefanD. Renkard3, JürgenM. Aguhnb, D. Ietm Ar Knoppik3Requires cookie*
 Title    Simultaneous Gas-Exchange and Fluorescence Measurements with Ozone-Fumigated Spruce  
 Abstract    A method was developed for carrying out gas-exchange and chlorophyll-fluorescence measurements simultaneously during fumigation of spruce twigs with peroxidic photooxi­ dants. It is thus now possible to investigate how a pollutant affects distinct sectors of the photosynthetic apparatus of the plant: whereas fluorescence reveals any changes in the pri­ mary light reaction, C 0 2 gas-exchange measurements supply information about the bio­ chemical reactions of the Calvin cycle. Results of short-time fumigation with 750 ppb ozone are presented here. Gas-exchange and fluorescence data are affected strongly in early sum­ mer, but not in autumn. The assimilation rate decreases significantly: primarily as a result of Rubisco activity and possibly because of direct inhibition of the electron-transport chain as well. Closure of the stomata leads to further reduction in the assimilation rate. Though no damage becomes visible on the needles, the perturbance of the photosynthetic apparatus caused by ozone fumigation is not reversible within 24 h. 
  Reference    Z. Naturforsch. 49c, 819—833 (1994); received June 21 1994 
  Published    1994 
  Keywords    Spruce, Photosynthetic Apparatus, Gas Exchange, Chlorophyll Fluorescence, Ozone Fumigation 
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 TEI-XML for    default:Reihe_C/49/ZNC-1994-49c-0819.pdf 
 Identifier    ZNC-1994-49c-0819 
 Volume    49 
2Author    Domingo Morales3, Juliane Peters3, M. Soledad, Jim Énez3, Michael Tauszb, Astrid Wonischb, Dieter GrillbRequires cookie*
 Title    Gas Exchange of Irrigated and Non-Irrigated Pinus canariensis Seedlings Growing Outdoors in La Laguna, Canary Islands, Spain  
 Abstract    Chlorophyll fluorescence, gas exchange, water potential and relative water content were measured in the needles of five year old seedlings of Pinus canariensis in order to know their response to mild water stress. Two trial plots of ten plants per plot, of similar age and characteristics were irrigated daily until the experiment was undertaken, then one of the plots was left without watering while the other one was irrigated as before. After a week of treatment, the water potential at midday did not change in any of the irrigated or non-irrigated plants maintaining around -0 .4 MPa, and the relative water content changed from 93% in irrigated to 84% in non-irrigated seedlings. The stomatal conductance decreased 60% in non irrigated plants and as a result C 0 2 assimilation decreased by 50% and transpiration was reduced at a higher proportion (70%), indicating a good control against water loss, before any change in water status in the needles could be observed suggesting an isohydric water economy in this plant. 
  Reference    Z. Naturforsch. 54c, 693—6 (1999); received December 14 1998/March 21 1999 
  Published    1999 
  Keywords    Pinus canariensis, Mild Water Stress, Gas Exchange, Water Potential, Chlorophyll Fluorescence, Seedlings 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0693.pdf 
 Identifier    ZNC-1999-54c-0693 
 Volume    54