An experimental study of intraspecific competition within several forage crops

Binary or complex mixtures of populations within one species (cocksfoot Dactylis glomerata L., tall fescue Festuca arundinacea Schreb., lucerne Medicago sativa L. and red clover Trifolium pratense L.) were made in Italy, at Lodi or Roma. Taken together, the experimental results showed the importance of the relation- ship between homogeneity of species composition and yield in explaining the performance and outcome of the associations. Intraspecific association did not seem to be of agronomic importance : instead, the internal structure of the sward should be adjusted towards greater homogeneity of stand composition. Associations always involved competition, at both the population and individual plant level. Departures from this general rule are discussed.