Carbon Metabolism of Micropropagated Rosa multiflora L

To quantify the C-metabolism in micropropagated roses, two labeled substrates were tested:$^{14}C-sucrose$and14CO2. In the$^{14}C-sucrose$experiment four parameters were followed during the culture period: the decrease of the radioactivity of the culture medium (by liquid scintillation counting), the dry matter accumulation, the radioactivity of the dry matter, and the radioactivity of the captured CO2. These values were related to the total sucrose uptake, the total biomass increase, the biomass increase by sucrose incorporation, and the sucrose respired as CO2. C-incorporation during photosynthesis was calculated as the difference between total biomass increase and biomass increase by sucrose incorporation. The14CO2experiment did not allow measurement of the net CO2fixation in a direct way because the ratio of14CO2over total CO2in the headspace of the container could not be kept constant over the culture period. Respiration caused a build up of the CO2concentration in the headspace. Indirect calculation established a comparable photosynthetic portion of CO2uptake for the tested variety.