An Assessment of the Role of Planting Density in Competition between Red Clover (Trifolium pratense L.) and Lucerne (Medicago sativa L.) in the Early Vegetative Stage

Abstract

where differences between the yield: plant density relationships of the two species should be taken into account. It may readily be envisaged that a plant in which maximum weight is reached at a relatively low density would outyield at low densities a species in which a higher density is required before maximum yield is obtained, whilst at higher densities no such difference might be observed, or a reversal of trend might occur. An opportunity to examine this situation presented itself when the author was visiting Sweden on study leave, and it was decided to conduct an experimental analysis of competition between two pasture legumes grown together over a wide range of densities, and to include in the experimental material pure stands of each species in order that their yield: density relationships could be accurately determined. It was thought that two species should be chosen which were sufficiently similar in growth habit as not to cause marked differences in yield : time relationships, but which were nevertheless sufficiently contrasting as to present a marked degree of interspecific competition. In view of the recent interest shown in the suitability of mixtures of lucerne and red clover in Swedish agriculture (ABERG 1956, LAGERQUIST 1958) these two species, which satisfied the conditions put forward above,