RESPIRATION IN RELATION TO NITROGEN-CONTENT IN THE BIOMASS OF ITALIANRYEGRASS

We investigated respiration as a function of nitrogen concentration in the biomass of Italian ryegrass (Lolium multiflorum Lam.). Plants wer e grown at different supplies of mineral nitrogen. Ones from fertilize d plots (12 and 3 g of N/m2) differed in dry mass from plants from unf ertilized plots. Reliable differences of nitrogen content between plan ts of the above-indicated variants were recorded only in young plants. In calculation per unit of biomass, the respiration rate was the same in all growth variants and declined in the process of plant ontogenes is from 5 to 1.5 mg of CO2.g-1.h-1. The relations of both the respirat ion rate and the relative growth rate to concentration of reduced nitr ogen in the biomass are described by the same function. Linear regress ion of growth to respiration also indicates a monotypic nature for the dependency of ontogenetic changes in the respiration rate and relativ e growth rate on nitrogen content. The obtained data enable us to asse rt that the ontogenetic relation of respiration to nitrogen is mediate d through the growth function of the plant.