Comparison of CO sub 2 assimilation rate with photosynthetic electron transport rates in needles of douglas fir exposed to moderate concentrations of SO sub 2 , NO sub 2 or NH sub 3

Conference · Tue May 01 04:00:00 EDT 1990 · Plant Physiology, Supplement; (USA)

OSTI ID:5726189

van Kooten, O; van Hove, L W.A.; Mensink, M; Vredenberg, W J ^[1]

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1. Wageningen Agricultural Univ. (Netherlands)

Two year old douglas firs (Pseudotsuga menziesii) were exposed to 80 {mu}g m{sup 3} of SO{sub 2}, NO{sub 2} or NH{sub 3} or a combination of these gases for 5 months. Needles which had sprouted during the treatment were measured. Light response curves of electron transport rates were deduced from chlorophyll fluorescence measurements by the method proposed by Genty et al. Light response curves of net CO{sub 2} assimilation rates were determined on the same needles in a conventional gas exchange leaf cuvette. The maximum electron transport rate was reduced to between 75 and 50% of the control plants (filtered air). In the gas exchange measurements the same results were obtained for all plants exposed to SO{sub 2}, with the severest reduction in needles exposed to combined SO{sub 2} and NO{sub 2}. Plants exposed to NO{sub 2}, NH{sub 3} or a combination thereof revealed no reduction in the maximum net CO{sub 2} assimilation rate. Measurements of the total chlorophyll content of these needles however revealed an increase. When the diminution in maximum electron transport rate was multiplied with the enhancement of the chlorophyll content in the needles exposed to excess gaseous nitrogen, the minimal change in CO{sub 2} assimilation rate could be accounted for. However this relationship broke down in the needles fumigated with SO{sub 2} and the relationship between electron transport and net photosynthesis became straight forward.

• OSTI ID: 5726189
• Report Number(s): CONF-9007196--
• Conference Information: Journal Name: Plant Physiology, Supplement; (USA) Journal Volume: 93:1
• Country of Publication: United States
• Language: English

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