Document: JAC-3-38-7

Increasing the suppression of weeds by cereal crops.

WEINER, J.*, H.GRIEPENTROG and L.KRISTENSEN

Royal Veterinary and Agricultural University, Frederiksberg, Denmark ¹

Abstract:
Recent advances in our understanding of the size-advantage in competition among individual plants suggest that the potential for many crops to suppress weeds is much greater than generally appreciated, and that this potential can be realized if (a) the crop density is increased significantly, and (b) the crop is hyperdispersed (uniformly distributed) in two-dimensional space rather than sown in traditional rows. We tested this hypotheses by sowing four varieties of spring wheat at three densities (200, 400 and 600 m^-2) and in two spatial patterns (normal rows and a hyperdispersed grid pattern) in the presence of high weed pressure. There were strong and significant effects of both crop density and spatial distribution on weed growth and resultant yield losses. Weed biomass was 30% lower in the uniform pattern. The treatment with high crop density and a uniform sowing pattern contained 60% less weed biomass and produced 60% higher yield than the treatment reflecting normal sowing practices (crops sown in rows at 400 m^-2). The results were similar when the experiment was repeated in the following year, even though the weed community was very different. A more crowded, uniform distribution of many crops can contribute to a strategy to reduce the use of herbicides and energy-intensive forms of weed control.

Keywords: crop-weed competition

This abstract is being presented at: 3:30 PM in session:
Oral Session #31: Agroecology.