Relationship Between Photosynthesis and Respiration in Leaves Using 13C/12C Isotope Labelling

摘要

The relationship between photosynthesis and respiration was studied in four plant species (Ranunculus glacialis, Chamaerops humilis, Phaseolus vulgaris and Fagus sylvatica) using 13C/12C stable isotopes. This study was conducted using an open gasexchange system coupled to an elemental analyzer and linked to an isotope ratio mass spectrometer (IRMS). We showed that the carbon recently assimilated during photosynthesis accounts for ca. 50% of the carbon in the CO2 lost by dark respiration after illumination in Phaseolus vulgaris and Fagus sylvatica, and less than 10% in Ranunculus glacialis and Chamaerops humilis. Therefore, most of the carbon released by dark respiration after illumination in leaves does not come from 'new' photosynthates.