ISSN:
0931-1890
Keywords:
Key words Light response curve
;
Chamaecyparis obtusa
;
Elevated CO2
;
Temperature
;
Net photosynthesis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Two branches of a field-grown Chamaecy-paris obtusa tree were enclosed in chambers of an open gas exchange system for continuous CO2 exchange measurements. One branch was subjected to ambient air (CO2, 370 µmol mol–1) and the other was subjected to CO2-enriched air (800 µmol mol–1). The CO2 exchange rate of the branches, air temperature and photosynthetic photon flux density were recorded every 4 min by a computer during the two experimental periods of July 1994 to June 1995 (experiment 1) and April 1996 to August 1997 (experiment 2). The response of CO2 gas exchange rate to light changed with the seasonal temperature. The highest saturated rate of net photosynthesis on a leaf area basis was observed in May and October in both CO2 treatments when the mean daytime temperature was about 18–19°C. This temperature was almost equal to the yearly mean daytime temperature. Above and below this temperature, the saturated net photosynthesis rate decreased. The net photosynthesis rate was usually higher in the elevated CO2 treatment. The ratio of monthly net photosynthesis rate in elevated CO2 to that in ambient CO2 was linearly related to the monthly mean daytime temperature. This ratio increased by 3.3% for each 1°C increase in the monthly mean daytime temperature; the highest ratio of 1.8 occurred in August. When the ratio was 1.0, the temperature was about 5–6°C, which was close to the mean daytime temperature of the coldest month. Elevated CO2 increased per unit area net photosynthesis by 38.5% and 43.7% in experiments 1 and 2, respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00009769
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