DAILY BALANCE OF CANOPY CO₂-EXCHANGE: A WAY TO PREDICT SEASONAL DRY MATTER PRODUCTION AND CO₂ DEMAND – REFEREED PAPER –

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.

IV International Symposium on CO2 in Protected Cultivation

G. Adaros

https://doi.org/10.17660/ActaHortic.1990.268.2