ISHS Acta Horticulturae 268: IV International Symposium on CO2 in Protected Cultivation
DAILY BALANCE OF CANOPY CO2-EXCHANGE: A WAY TO PREDICT SEASONAL DRY MATTER PRODUCTION AND CO2 DEMAND - REFEREED PAPER - |
| Author: | G. Adaros |
| Abstract:
During the time between June and November 1980, 4 pot-plant cultures of Phaseolus vulgaris L. cv. Sancy grown in a greenhouse were available for CO2-exchange measurements in a dailit, dewpoint-controlled growth chamber. Automatically controlled, constant air flows supplied CO2 in varying concentrations similar to the situation in greenhouses. CO2 concentration of inlet and outlet air was continuously monitored. Both in the course of plant development and of year, series of measurements of 3 or 4 d of CO2 exchange and dry matter production of a plant stand of 6 to 15 plants under varying natural light conditions were conducted. In this way, the daily average and daily sum of net photosynthesis and dark respiration, the daily balance of CO2 exchange, and the growth rate were calculated. With aging of plants photosynthetic (P) and respiration rate (R) per unit of leaf area declined, whereas the rates per plant still increased. A high positive correlation between P and R was observed. The daily sum of both parameters and the ratio between both changed considerably with time. The ratio of CO2 fixation/biomass production declined in the course of season; the average was 1.5 g CO2 per g dry matter. | |
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