Competition between Chondrilla juncea and Trifolium subterraneum: the influence of canopy areas and heights

Abstract

Growth in the field of Chondrilla juncea and Trijolium subterraneum at different nitrogen levels was compared during late vegetative and early reproductive phases in monocultures and mixed stands. Observed differences between the species in terms of relative growth rates and net assimilation rates in monocultures were not reflected in the performance of the species in competitive mixtures. A major factor contributing to this anomaly was the different leaf distribution of the two species in mixtures.The annual T. subterraneum produced a larger area of leaf at a higher level in the canopy than did the perennial C. juncea.The crowding coefficient of C. juncea with respect to T. subterraneum was significantly less than 1, indicating that T. subterraneum was more competitive than C. juncea.Applications of nitrogen at a late stage of growth did not change the competitive ability of the species.Some limitations of the experimental procedure and of the de Wit competition analysis are discussed.