SOURGRASS INTERFERENCE ON SOYBEAN GROWN IN BRAZILIAN CERRADO

ALINE GUIMARÃES CRUVINEL,GUILHERME BRAGA PEREIRA BRAZ,RUBEM SILVÉRIO DE OLIVEIRA JÚNIOR,ALAN BRUNO CANEPPELE,ALESSANDRO GUERRA DA SILVA,HUDSON KAGUEYAMA TAKANO

doi:10.1590/1983-21252021v34n211rc

ALINE GUIMARÃES CRUVINEL, GUILHERME BRAGA PEREIRA BRAZ + Show 4 more

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https://doi.org/10.1590/1983-21252021v34n211rc

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Abstract

ABSTRACT Sourgrass (Digitaria insularis) is one of the main species causing significant losses in Brazilian soybean production systems. Thus, this paper aimed to evaluate sourgrass interference on soybeans grown under Cerrado conditions. Three field experiments were conducted, of which the first two (E1 and E2) simulated sourgrass after pre-sowing burndown, using plants already emerged by the time soybeans were sown; whereas the third (E3) simulated both sourgrass and soybeans emerged simultaneously. Both E1 and E2 were conducted in a randomized complete block design (RCBD) with five treatments based on sourgrass infestation densities (0, 2, 4, 6, and 8 plants m-2) and four replications. In turn, E3 was also carried out in an RCBD but with treatments arranged in a 2 x 5 factorial and four replications. The first factor comprised two soybean cultivars, while the second was sourgrass density levels, just as in E1 and E2. The results showed that increasing sourgrass densities reduced soybean yield regardless of the plant growth stage when the crop was sown. Yield losses were higher when sourgrass plants were already established by the time soybean was sown. Soybean yield losses reached up to 80% under higher sourgrass infestation levels.

Highlights

Weed resistance to herbicides has been causing financial losses to growers due to weed interference and increased production costs (HEAP; DUKE, 2018)
In Brazil, costs of herbicide resistance management in soybeans are estimated to be approximately 1.25 billion dollars annually, and this could reach up to 2.3 billion dollars, including yield losses caused by weed interference (ADEGAS et al, 2017)
A linear increase in soybean height was observed by increasing sourgrass density for both locations at 14 and 35 days after crop emergence (DAE) (Figure 2); soybean plants etiolated in response to the shading exerted by sourgrass plants

Summary

Introduction

Weed resistance to herbicides has been causing financial losses to growers due to weed interference and increased production costs (HEAP; DUKE, 2018). In Brazil, costs of herbicide resistance management in soybeans are estimated to be approximately 1.25 billion dollars annually, and this could reach up to 2.3 billion dollars, including yield losses caused by weed interference (ADEGAS et al, 2017). The evolution of glyphosate resistance has typically increased problems, especially because this herbicide is one of the most used in agriculture and sue to the broad adoption of genetically engineered crops able to withstand post-emergence glyphosate applications (DUKE; POWLES; SAMMONS, 2018). Any weed species evolving glyphosate resistance can become a significant problem to agriculture in those areas (SAMMONS; GAINES, 2014)

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