Competition among pasture plants. I. Intraspecific competition among annual pasture plants

Abstract

A series of experiments was conducted to examine the influence of density, stage of growth, and fertility level on intra-specific competition among annual pasture plants. At sowing there is a linear relationship between density and yield (weight of embryos or embryo + endosperm per unit area). Competition is evident in dense populations shortly after germination and thereafter becomes operative progressively in populations of lower and lower density. Because of the extreme reduction in growth rate in dense swards later in the season and the high growth rate in sparse swards, the sparse sward tends to approach the more dense sward in its final yield. Final yield of dry matter is constant from moderate to high densities. There is no reduction in dry matter per unit area even in extremely dense swards. This maximum yield of dry matter for the environment is controlled by some factor of the environment. It is considered that nitrogen was the factor in two of the experiments here reported and light in the third. The significance of light in competition in pastures is discussed. Practical applications of these findings are discussed.