Comparative growth and competition of wild radish (raphanus raphanistrum L.) and wheat

Abstract

The effects of various densities of wild radish (Raphanus raphanistrum L.) and wheat on the growth and reproductive output of each other were investigated in a field trial at Roseworthy, South Australia in 2003. The experiment was established as a factorial combination of wheat (0, 100, 200 and 400 plants/m²) and wild radish (0, 15, 30 and 60 plants/m²) densities. The presence of wild radish in wheat reduced shoot dry matter and grain yield of wheat with the magnitude of this reduction dependent on weed density. The variation in wheat grain yield was largely related to the changes in the density of wheat ears. Increasing the density of wheat substantially reduced the adverse effects of wild radish on wheat. As crop density increased, weed dry matter and pod production per unit area decreased. Wild radish pod weight/m² was negatively correlated with wheat density (r = -0.70, P < 0.01) and wheat grain yield (r = -0.81, P < 0.01). This indicated that higher densities of wheat were able to suppress pod production of this weed species. From a practical view point, this study shows that increased wheat density in the range of 200-300 wheat plants/m² can reduce wild radish pod production and may also give some reduction in crop yield loss. The data collected will be used to develop a simulation module based on the APSIM platform.