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vol.27 issue1Accumulation of macro and micronutrients by soybean and Brachiaria brizantha emerged in different periodsWeed interference periods in ratoon sugarcane author indexsubject indexarticles search
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Planta Daninha

Print version ISSN 0100-8358On-line version ISSN 1806-9681


SILVA, A.F. et al. Period before interference in soybean-RR crop under low, medium and high infestation level conditions. Planta daninha [online]. 2009, vol.27, n.1, pp.57-66. ISSN 0100-8358.

The aim of this study was to evaluate the period before weed interference in soybean culture, cv. BRS 243-RR, under low, medium and high weed density. The experimental design was arranged in complete randomized blocks, and the treatments consisted of increasing periods of weed control (0, 0-5, 0-10, 0-15, 0-21, 0-28, 0-35, 0-42, 0-49 and 0-125 days). In low weed infestation area the main weed species were: Brachiaria plantaginea,Ipomoea nil,Euphorbia heterophylla. In medium and high infestation areas, Brachiaria plantaginea,Ipomoea nil,Digitaria horizontalis and Cyperus rotundus were the most frequent weeds. Considering 5% and 10% of tolerance of soybean grain yield reduction, it was concluded that the period before interference was 17 and 24 days after emergence (DAE) in low infestation, area 11 and 15 DAE in medium infestation area and 11 and 16 DAE in high infestation area. Weed interference during the full crop cycle reduced soybean grain yield in 73%, 82% and 92%, for low, medium and high weed density, respectively.

Keywords : competition; critical periods of competition; Glycine max.

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