Ferrugem asiática da soja : resistência, controle químico e tolerância

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The asian soybean rust (ASR) caused by Phakopsora pachyrhizi Syd. &P. Syd. is the most destructive leaf disease of this culture. The objective of this study was to assess forms of resistance to complement traditional qualitative resistance (vertical), through studies of quantitative resistance (horizontal) and tolerance, conditioned by minor genes, which may express lower rate of disease progress and protect the yield potential, among other responses of resistance. The tests were conducted in Cambé, PR, Brazil in the 2006/07 and 2007/08 growing seasons. To identify the presence of horizontal resistance were evaluated: type of lesion, sporulation intensity, severity, number of lesions and uredinias and urediniospores yield of 48 genotypes. It was possible to separate the genotypes into four distinct groups, with different degrees of qualitative and quantitative resistance responses, with possibilities of groups B, C and D been used as promising sources of genes for resistance to ASR. To evaluate the effect of vertical resistance and chemical control were assessed: severity, yield and defoliation in susceptible cultivar BRS 133, and the resistant strain CB06-953/963 in three experiments. The presence of the Rpp4 gene in the resistant strain was shown to be effective in reducing the progress of ASR. Especially in conditions of high inoculum pressure, the applications of fungicides, helped to control the ASR and the maintenance of yield in the resistant cultivars. To understanding the effect of chemical control and tolerance to P. pachyrhizi, severity of ASR and productivity in commercial cultivars of soybean were evaluated. The efficiency of fungicides in the control of ASR varied with the cultivars studied, in the two growing seasons, and it was not possible to identify the presence of tolerance under conditions in which the experiments were conducted.

ASSUNTO(S)

soja - ferrugem asiática plantas - efeito dos fungicidas phakopsora pachyrhizi soy-bean soja - resistência a doenças e pragas disease and pest resistance

ACESSO AO ARTIGO

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