Comportamento de Ralstonia solanacearum de eucalipto em solo contendo glifosato
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Data
2021-11-26
Autores
Henrique, Ródney Lúcio Pinheiro
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Universidade Estadual Paulista (Unesp)
Resumo
A Ralstonia solanacearum é um dos principais patógenos do eucalipto por ser causadora da murcha bacteriana, doença que tem sido fator limitante na cultura. A bactéria é um patógeno de solo com hábitos saprofíticos e é capaz de interagir com a microbiota e elementos do solo em que vive. Diante do exposto e sabendo que herbicidas amplamente utilizados em plantios de eucalipto, como o glyphosate, podem deixar resíduos no solo, o presente trabalho teve como objetivo analisar o comportamento de R. solanacearum isolada de eucalipto em solo contendo doses de glyphosate. Para a realização dos experimentos a solução bacteriana foi preparada e inoculada em solo estéril, na presença de mudas de eucalipto, tratadas com diferentes doses de glyphosate. Foram utilizados sete tratamentos: solo; solo + R. solanacearum; solo + R. solanacearum + dose recomendada de glyphosate (0,36 mg e.a. L-1 ); e para os tratamentos seguintes as doses foram sendo dobradas até alcançar a dose de 16 vezes (0,72 mg e.a. L-1 , 1,44 mg e.a. L-1 , 2,88 mg e.a. L-1 e 5,76 mg e.a. L-1 , respectivamente). O delineamento experimental utilizado foi inteiramente casualizado, com 10 repetições por tratamento, totalizando 70 parcelas experimentais. Foi realizada a quantificação da população bacteriana de amostras de solo dos tratamentos em diferentes períodos, em meio de cultura Kelman, além de análise da atividade das enzimas peroxidase e fenilalanina amônia-liase, ligadas à defesa da planta. Também foram realizadas análises morfofisiológicas das plantas e análise respirométrica do solo. Houve aumento da população da bactéria no solo com o aumento das doses do herbicida, havendo diminuição apenas nas doses mais altas. Os tratamentos que continham glyphosate interferiram na atividade das enzimas analisadas, onde sobredoses aumentaram a atividade de peroxidase e diminuíram a atividade de fenilalanina amônia-liase. Doses de glyphosate induziram a maior produção de biomassa. A presença do glyphosate apresentou aumento na respiração do solo com presença do patógeno, principalmente no tratamento com 8 vezes a dose recomendada. A utilização de glyphosate no controle de plantas daninhas na cultura do eucalipto apresentou interação com R. solanacearum, necessitando de estudos mais específicos.
Ralstonia solanacearum is one of the main pathogens of eucalyptus as it causes bacterial wilt, a disease that has been a limiting factor in the culture. The bacterium is a soil pathogen with saprophytic habits and is able to interact with the microbiota and soil elements in which it lives. Given the above and knowing that herbicides widely used in eucalyptus plantations, such as glyphosate, can leave residues in the soil, this study aimed to analyze the behavior of R. solanacearum isolated from eucalyptus in soil containing doses of glyphosate. To carry out the experiments, the bacterial solution was prepared and inoculated in sterile soil, in the presence of eucalyptus seedlings, treated with different doses of glyphosate. Seven treatments were used: soil; soil + R. solanacearum; soil + R. solanacearum + recommended dose of glyphosate (0.36 mg e.a. L-1 ); and for the following treatments the doses were doubled until reaching a dose of 16 times (0.72 mg a.e. L-1 , 1.44 mg a.e. L-1 , 2.88 mg a.e. L-1 and 5.76 mg e.a. L-1 , respectively). The experimental design used was completely randomized, with 10 replications per treatment, totaling 70 experimental parcels. The quantification of the bacterial population of soil samples from the treatments at different periods was carried out, in Kelman culture medium, in addition to the analysis of the activity of the enzymes peroxidase and phenylalanine ammonia-lyase, linked to plant defense. Morphophysiological analyzes of the plants and respirometric analysis of the soil were also carried out. There was an increase in the population of bacteria in the soil with increasing doses of the herbicide, with a decrease only in the highest doses. The glyphosate treatments interfered in the activity of the analyzed enzymes, where overdoses increased the peroxidase activity and decreased the phenylalanine ammonia-lyase activity. Glyphosate doses induced the highest biomass production. The presence of glyphosate showed an increase in soil respiration with the presence of the pathogen, especially in the treatment with 8 times the recommended dose. The use of glyphosate to control weeds in the eucalyptus crop showed interaction with R. solanacearum, requiring more specific studies.
Ralstonia solanacearum is one of the main pathogens of eucalyptus as it causes bacterial wilt, a disease that has been a limiting factor in the culture. The bacterium is a soil pathogen with saprophytic habits and is able to interact with the microbiota and soil elements in which it lives. Given the above and knowing that herbicides widely used in eucalyptus plantations, such as glyphosate, can leave residues in the soil, this study aimed to analyze the behavior of R. solanacearum isolated from eucalyptus in soil containing doses of glyphosate. To carry out the experiments, the bacterial solution was prepared and inoculated in sterile soil, in the presence of eucalyptus seedlings, treated with different doses of glyphosate. Seven treatments were used: soil; soil + R. solanacearum; soil + R. solanacearum + recommended dose of glyphosate (0.36 mg e.a. L-1 ); and for the following treatments the doses were doubled until reaching a dose of 16 times (0.72 mg a.e. L-1 , 1.44 mg a.e. L-1 , 2.88 mg a.e. L-1 and 5.76 mg e.a. L-1 , respectively). The experimental design used was completely randomized, with 10 replications per treatment, totaling 70 experimental parcels. The quantification of the bacterial population of soil samples from the treatments at different periods was carried out, in Kelman culture medium, in addition to the analysis of the activity of the enzymes peroxidase and phenylalanine ammonia-lyase, linked to plant defense. Morphophysiological analyzes of the plants and respirometric analysis of the soil were also carried out. There was an increase in the population of bacteria in the soil with increasing doses of the herbicide, with a decrease only in the highest doses. The glyphosate treatments interfered in the activity of the analyzed enzymes, where overdoses increased the peroxidase activity and decreased the phenylalanine ammonia-lyase activity. Glyphosate doses induced the highest biomass production. The presence of glyphosate showed an increase in soil respiration with the presence of the pathogen, especially in the treatment with 8 times the recommended dose. The use of glyphosate to control weeds in the eucalyptus crop showed interaction with R. solanacearum, requiring more specific studies.
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Palavras-chave
Murcha bacteriana, Herbicida, Biodegradação, Fenilalanina, Peroxidase, Bacterial wilt, Herbicide