| Abstrakt: |
Development of an integrated weed management system requires detailed information on crop‐weed interactions, including the impact of the relative competitive ability of the crop during various phases of development on weed growth. The objective of this study was to quantify effects of maize (Zea maysL.) plant density on weed interference in maize throughout the growing season. Experiments were carried out during 1990, 1991, and 1992 at the Elora Research Station, Elora, ON, on a London loam (Aquic Hapludalf) soil that had been tile drained. Maize was grown at three plant densities (4, 7, and 10 plants m−2) under three weed pressures. Weed pressures were established by varying the weedfree period after maize planting: all season (weed free), planting to 5‐ to 7‐leaf stage of maize (medium weed pressure), and planting to 3‐ to 4‐leaf stage of maize (high weed pressure). Maize and weed biomass and composition were evaluated at 3 wk presilking, silking, 3 wk postsilking, and at physiological maturity. Maize leaf area index, leaf chlorophyll content, and photosynthetic photon flux density transmittance with and without weeds were also measured. Increasing maize plant density from 4 to 10 plants m−2reduced weed biomass by up to 50%. The impact of high weed‐pressure treatments on maize dry matter accumulation remained in a narrow range of 18 to 21% throughout the growing season. The grain yield reductions attributable to high weed pressure were 26, 17, and 13% for the maize plant densities of 4, 7, and 10 plants m−2, respectively. Results of this study show that the competitiveness of maize with weeds can be enhanced by increasing plant density. |
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