Suppression of weeds by spring wheat Triticumaestivum increases with crop density and spatial uniformity

Abstract

Summary1. Recent advances in our understanding of the advantage of initial size in competition among individual plants (size-asymmetric competition) suggest that the potential for many crops to suppress weeds is much greater than generally appreciated. We hypothesize that this potential can be realized if: (i) the crop density is increased significantly and (ii) the crop is regularly (uniformly) distributed in two-dimensional space rather than sown in traditional rows. 2. We tested these hypotheses by sowing four varieties of spring wheat Triticum aestivum at three densities (200, 400 and 600 m -2 ) and in two spatial patterns (normal rows and a uniform grid pattern) in the presence of high weed pressure. 3. There were strong and significant effects of both crop density and spatial distribution on weed growth. Weed biomass decreased with crop density and was 30% lower in the grid pattern. 4. There was a negative linear relationship between above-ground weed biomass in early July and crop yield at harvest, so weed suppression translated directly into yield. The treatment with high crop density and the grid sowing pattern contained 60% less weed biomass and produced 60% higher yield than the treatment closest to normal sowing practices (crops sown in rows at 400 m -2 ). 5. The results were similar when the experiment was repeated in the following year, even though weed abundance was lower and the weed community was very different. There was 30% less weed biomass and 9% higher yield when the crop was sown in a grid pattern. 6. While weed biomass decreased monotonically with density for all varieties, a significant variety-density interaction suggested that the attributes resulting in good weed suppression at high crop density may not be the same as those most advantageous at low crop density. 7. A more crowded, uniform, distribution of some crops could contribute to a strategy to reduce the use of herbicides and energy-intensive forms of weed control.

Spring wheat yield response to variable seeding rates in organic farming systems at different fertility regimes

“…Seeding rate has been shown to be a useful cultural control to reduce weed competition in conventionally grown crops. Increased seeding rate can reduce weed biomass and weed seed production (Wilson et al 1995;Weiner et al 2001;Korres and Froud-Williams 2004). At higher densities, wheat is expected to be at a competitive advantage by more effectively competing with weeds for resources (Mohler 1996).…”

Integration of mulching and row spacing on weed management in Green Pepper varieties

“…In a study by Kaur et al (2002) have shown that even seed distribution increases crop establishment and per unit area and thus resulting in higher competitiveness against weeds. In another experiment, significant effects of both crop density and spatial distribution on weed growth were observed (Weiner et al 2001). They further reported that high crop density and grid sowing pattern recorded 60% less weed biomass and produced 60% higher yield as compared to lower crop densities and normal sowing in rows.…”

Influence of wheat populations arrangement on growth characteristics and grain yield

“…This modification can improve plants' water usage due to lower interspecific competition and consequently greater water supply during critical periods. It also allows greater solar radiation penetration inside the canopy, increased air flow and also improves pesticide application quality, especially fungicides (Weiner et al 2001).…”