Chemical Control and Morphoanatomical Analysis of Leaves of Different Populations of Sourgrass

Abstract

-Digitaria insularis has been selected by frequent glyphosate applications both in no-till areas and in fruit orchards. The objective of this paper was to evaluate control efficacy of D. insularis populations by glyphosate, alone and mixed with quizalofop-p-tefuryl, as well as classify them for herbicide sensitivity as susceptible, moderately susceptible and tolerant. This study also aimed to evaluate the relations between herbicide sensitivity and morphoanatomic features of leaf tissues. For chemical control, the experiment was conducted in a completely randomized design, with a 12 x 4 factorial arrangement with four replications. Twelve populations of D. insularis were treated with glyphosate alone at two concentrations (1.44 and 2.16 kg a.e. ha -1 ) and with the mixture of glyphosate (2.16 kg a.e. ha -1 ) and quizalofop-p-tefuryl (0.12 kg a.i. ha -1 ). One treatment without herbicide application was maintained for each plant population. Evaluations about the morphoanatomic features and wax content of leaves from the twelve plant populations were made under laboratory conditions. Populations 3, 5, 6 and 8 were considered to be susceptible; 9, 10 and 12 were considered as moderately susceptible; 1, 2, 4, 7 and 11 were considered tolerant to glyphosate. However, populations within each group (susceptible, moderately susceptible and tolerant) did not have similar characteristics that justify their response to glyphosate. Differences relative to herbicide translocation and/or plant physiology could account for the chemical control results for these populations.Keywords: Digitaria insularis, glyphosate, tolerance, genetic variability. RESUMO -A espécie

<b>Glyphosate efficacy on sourgrass biotypes with suspected resistance collected in GR-crop fields

“…In addition, some researchers have shown the high susceptibility of sourgrass to this herbicide, documenting GR 50 values lower than 100 g ae ha -1 for susceptible biotypes (Carvalho et al, 2011;Reinert, Prado, & Christoffoleti, 2013). However, farmers widely apply greater than the recommended field dose, such as 1,440 g ae ha -1 (Carvalho et al, 2012;Melo, Rosa, Brunharo, Nicolai, & Christoffoleti, 2012;Gomes, Santos, Gasparino, & Correia, 2017), causing higher selection pressure on sourgrass and other weeds.…”

Susceptibilidade diferencial ao herbicida glyphosate e capacidade de rebrota de populações de capim-amargoso

“…Outros estudos também constataram a variabilidade de resposta das populações de capim-amargoso ao glyphosate, o que reforça a seleção de populações, prevalecendo no campo as menos afetadas pelo herbicida (Correia et al, 2010, Correia et al, 2015, Gomes et al, 2017.…”

Alternativas De Manejo Químico De Capim-Amargoso Na Cultura Da Soja

“…Barroso et al (2014) observaram controle satisfatório utilizando glyphosate em mistura com haloxifope-pmetílico, cletodim e quizalofope-p-etílico. Gomes et al (2017) relataram sinergismo nas misturas entre glyphosate e quizalofope-p-etílico, ambos em Digitaria insularis. Resultados similares foram observados com o uso de glyphosate em mistura com cletodim e quizalofope-p-etílico em plantas de azevém (ROCKENBACH et al, 2015).…”