Resistência de genótipos de soja ao herbicida glyphosate

Abstract

RESUMO -Avaliou-se a resistência de dez genótipos de soja (Glycine max) ao herbicida glyphosate. Foi adotado o esquema fatorial 10 x 4, no delineamento em blocos casualizados, com quatro repetições. O fator A foi composto por dez genótipos de soja, e o B, por quatro doses de glyphosate. A aplicação do herbicida foi realizada no momento em que as plantas de soja apresentavam a segunda folha trifoliolada completamente desenvolvida. Avaliaramse os caracteres: intoxicação das plantas, número de nós da haste principal, altura das plantas e massa seca das plantas. Na avaliação da intoxicação de plantas, tanto aos quatro dias após a aplicação (DAA) do herbicida quanto aos 28 DAA, os genótipos convencionais apresentaram médias superiores estatisticamente em comparação com genótipos resistentes ao glyphosate (RR). Verificou-se que, nas avaliações realizadas ao 0 DAA ou aos 28 DAA sob 0,0 g e.a. ha 1 , as respostas dos genótipos foram diferentes em todos os caracteres avaliados, com exceção do número de nós aos 28 DAA. Essas diferenças podem ser atribuídas aos efeitos fisiológicos e ambientais ou a características do próprio material. Nas demais doses, os genótipos RR comportaram-se de maneira desejável em detrimento dos genótipos convencionais. Ao considerar todos os caracteres avaliados, pode-se afirmar que Valiosa RR, BCR945G110, BCR945G114, BCR892G132, BCR892G140, BCR1067G210, BCR1070G244 e M-SOY 8008RR comportaram-se de forma semelhante quanto à resistência ao glyphosate quando submetidos até a dose de 2.160 g e.a. ha ABSTRACT -Resistance of ten soybean genotypes (Glycine max) to the herbicide glyphosate was evaluated. The randomized block experimental design was used under factorial scheme 10 x 4 and four replicates. Factor A was composed of 10 soybean genotypes and factor B of four glyphosate doses. The herbicide was applied when the second trifoliate leaf of the soybean plants was completely developed. The following characters were evaluated: plant intoxication, number of nodes at the main stem, plant height and dry mass. When evaluating plant intoxication either at four days after application (DAA) of the herbicide and at 28 DAA, the conventional genotypes showed statistically higher averages, compared to the glyphosate-resistant genotypes (RR). In evaluations accomplished at 0 DAA or at 28 DAA under 0.0 g e.a. ha -1 , the genotype responses were different for all characters under evaluation, except for the number of nodes at 28 DAA. These differences were attributed to the physiological and environmental effects or to the characteristics of the material itself. At other doses, the behavior of the RR genotypes was superior to that of the conventional ones. Taking into account all characters under evaluation, it can be stated that Valiosa RR, BCR945G110, BCR945G114, BCR892G132, BCR892G140, BCR1067G210, BCR1070G244 and M-SOY 8008RR behaved similarly for glyphosate resistance when subjected to doses up to 2.160 g e.a. ha -1 .

Performance of transgenic and conventional soybean plants subjected to bioassay for detection of glyphosate tolerant seeds

“…Other characteristics, such as dry weight of stems ( Figure 3D), number of branches in the main stem ( Figure 3E), and dry weight of pods ( Figure 3F) decreased at the application rates of 0.06% and 0.12% of the herbicide. In the case of plants tolerant to glyphosate, in general, there were no negative effects, as also reported by Kruse et al (2000), Matsuo et al (2009), and Correia and Durigan (2007). All these vegetative characteristics together showed that recovery of tolerant plants is satisfactory, but in the case of sensitive cultivars, there are persistent losses in the plant cycle due to the herbicide rate used in the germination bioassay (Albrecht et al 2014).…”

“…An assay performed by Gris et al (2013) showed that herbicide application on herbicide-tolerant plants under either field or greenhouse conditions, which would be more stressful conditions than germination in a moistened substrate with glyphosate, did not change seed physiological quality, confirming the result of plant recovery in this study. Matsuo et al (2009) did not observe symptoms from herbicide in tolerant plants after they were sprayed with glyphosate under Figure 1. Reduction in the hypocotyl (A), radicle (B), and seedling (C) length due to concentration of herbicide acid equivalent of 0, 0.03, 0.06, and 0.12 %.…”

“…For sensitive plants, recovery was less pronounced, but occurred. Matsuo et al (2009) also reported a certain recovery of strains sensitive to the herbicide. As for tolerant cultivars, the accumulation of biomass in tissues of agronomic interest may be affected as a function of herbicide Table 2.…”

“…Given the dynamics of the aims of plant breeding, it is natural that transgenic lines have many interesting characteristics for a breeding program. Herbicide-tolerant cultivars behave in a similar way and may be used for genetic improvement (Matsuo et al 2009). From hybridizations, segregating populations can be conducted in the search for superior genotypes, which may or may not include the transgenic trait.…”

Genetic diversity in soybean genotypes with resistance to Heterodera glycines

“…For soybean, analyses of genetic diversity have been widely applied. The presence of genetic variability among genotypes was observed by Miranda et al (2001), Miranda et al (2007), Matsuo et al (2009), Vieira et al (2009 and Almeida et al (2011). Also focusing on the soybean cyst nematode, Ma et al (2006) studied the genetic diversity of soybean and created a core collection based on this resistance.…”