Using a segmented nonlinear model it was possible to relate the biomass production per unit area and the plant weight of a solitary plant to competition in a monoculture. In a mixed population of 2 species or genotypes, the exchange rate describing the relation between the 2 competitors, was shown to be approximately constant throughout the period of growth. This constancy however, does not reveal an actual change in resource distribution in the same period. The ratio between the relative yield and the relative density of one competitor in relation to total yield and density, is a better description of the biomass distribution.
It is obvious from the results, that no single parameter can describe the complex situation of competition. On the other hand, 3 parameters in the nonlinear model explain between 90 and 95% of the variation in the very different competition situations observed in the 2 years trials. These are the weight of a single noncompeting plant, the asymptotic total yield of a population of an infinite number of plants and the 'exchange' rate between the 2 species.
The results from this project may constitute the basis for future test procedures. The data necessary in this context is the behaviour of the transgenic plant compared to the original nontransformed plant. The changes observed are then to be compared to the variation in competitiveness observed in related cultivars and species. The results from this project points out, that the dynamics in competition can be determined on the basis of the relevant growth curves in total yield and single plant weight.