Abstract:
The subject of the present thesis is the functional identification of the substrate pools forming the respiratory carbon supply system of intact plants of perennial ryegrass (Lolium perenne L.). In particular, it provides estimates of the number, size and turnover rate of pools and their relative importance (fractional contributions) as sources of carbon for shoot and root respiration, and it explores the effects of nitrogen fertilizer supply on substrate pool properties. The analysis was performed with plants growing in continuous light with either a low or a high nitrogen fertilizer supply. Plants were dynamically labeled with 13CO2/12CO2 for periods ranging from 1 h up to 1 month, followed by measurements of the rate and isotopic composition of respiration in shoots and roots, and compartmental modeling of the tracer kinetics in respiratory CO2