Relationship between plant density and yield for two spring cultivars of oilseed rape (brassica napus l.)

Yield/density relationships of two spring cultivars of oilseed rape were investigated under five different plant densities. Densities ranged from 20 to 130 plants m−2. Three response variables, number of pods per plant, seed weight per plant and dry matter per plant, were studied using different regression models to examine their relationship with density. Transformations were used to improve the fit of the models. Pods per plant, seed weight and dry matter per plant decreased as plant density increased. Seed weight and dry matter m−2 responded similarly to varying plant density for the two cultivars. For all response variables, the inverse exponential model gave the best fit to the data, indicating the existence of an optimum density, which was about half the official recommended sowing density.