Estimation of Mesophyll Conductance to CO2 Flux by Three Different Methods

摘要: The resistance to diffusion of CO2 from the intercellular airspaces within leaf through mesophyll sites carboxylation during photosynthesis was measured using three different techniques. techniques include a method based on discrimination against heavy stable isotope carbon, 13C, and two modeling methods. methods rely upon assumptions, but estimates conductance were similar with all leaves number species about 1.4 times stomatal for determined in unstressed plants at high light. relatively low partial pressure inside chloroplasts did not lead enhanced O2 sensitivity because caused significant drop chloroplast switching O2. We found no correlation between ratio internal area surface only weak proportion volume occupied by air. Mesophyll independent measurement, indicating that true physical parameter, biochemical effects, being measured. No evidence CO2-accumulating mechanisms found. Some plants, notably Citrus aurantium Simmondsia chinensis, had very conductances limit rate these can attain atmospheric level.