Caracterização de Rhizoctonia solani Kühn, agente causal da mela da soja (Glycine max (L.) Merrill), seleção de genótipos e controle químico
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Data
2002-02
Autores
Meyer, Maurício Conrado [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A mela da soja ocorre em várias regiões tropicais e subtropicais no mundo, sendo responsável por reduções de produtividade de até 50% nos EUA e de 31% no Brasil. A doença é causada pelo fungo Rhizoctonia solani AG1-IA e AG1-IB, com relatos do AG2-3 somente no Japão. No Brasil há incidência de mela nas regiões Norte, Nordeste e Centro Oeste. A caracterização do patógeno é fundamental para o estabelecimento de estratégias de controle e direcionamento de programas de melhoramento na busca de resistência genética. O controle químico representa a única alternativa após a instalação da doença, cuja eficiência varia em função das condições ambientais. O objetivo deste trabalho foi caracterizar o agente causal da mela da soja no Brasil, bem como desenvolver metodologia de seleção e avaliar a variabilidade genética em germoplasma de soja para resistência à doença, e o efeito de fungicidas e indutores de resistência sobre o patógeno e a doença. Isolados de R. solani provenientes do Mato Grosso, Maranhão, Roraima e Tocantins, foram analisados quanto às características citológicas, morfológicas, culturais e fusão de hifas para determinação do grupamento de anastomose...
Rhizoctonia foliar blight (RFB) of soybean occur on some world tropical and subtropical regions, causing yield reductions of 50% in USA and of 31% in Brazil. The disease is caused by Rhizoctonia solani AG1-IA and AG1-IB, and by AG2-3 only in Japan. The RFB occurs in Brazil in the North, Northeast and Mid-West regions of the country. The characterization of the pathogen is important for the establishment of disease control strategies and breeding for genetic resistance. Chemical control remains the only measure for controlling RFB after its incidence in a field, but its efficiency depends on the environmental conditions. The objectives of the present work were: characterization of Brazilian RFB isolates, screening methodologies and evaluation of soybean germplasm for genetic resistance, evaluation of fungicides and activators for their effects upon systemic acquired resistance on the R. solani and RFB. Isolates from the states of Mato Grosso, Maranhão, Roraima and Tocantins were analyzed for cytological, morphological, cultural and hyphal fusion characteristics. These isolates were also compared by Random Amplified Polimorfic DNA (RAPD) and by homology of rDNA-ITS sequence regions in order to define anastomosis group (AG) and Intraspecific Group (ISG) of the pathogen. Germplasm evaluation methodologies for resistance to RFB were compared by different inoculation methods. The effect of fungicides and activators of plant resistance were tested in vitro and in vivo...(Complete abstract, click electronic access below)
Rhizoctonia foliar blight (RFB) of soybean occur on some world tropical and subtropical regions, causing yield reductions of 50% in USA and of 31% in Brazil. The disease is caused by Rhizoctonia solani AG1-IA and AG1-IB, and by AG2-3 only in Japan. The RFB occurs in Brazil in the North, Northeast and Mid-West regions of the country. The characterization of the pathogen is important for the establishment of disease control strategies and breeding for genetic resistance. Chemical control remains the only measure for controlling RFB after its incidence in a field, but its efficiency depends on the environmental conditions. The objectives of the present work were: characterization of Brazilian RFB isolates, screening methodologies and evaluation of soybean germplasm for genetic resistance, evaluation of fungicides and activators for their effects upon systemic acquired resistance on the R. solani and RFB. Isolates from the states of Mato Grosso, Maranhão, Roraima and Tocantins were analyzed for cytological, morphological, cultural and hyphal fusion characteristics. These isolates were also compared by Random Amplified Polimorfic DNA (RAPD) and by homology of rDNA-ITS sequence regions in order to define anastomosis group (AG) and Intraspecific Group (ISG) of the pathogen. Germplasm evaluation methodologies for resistance to RFB were compared by different inoculation methods. The effect of fungicides and activators of plant resistance were tested in vitro and in vivo...(Complete abstract, click electronic access below)
Descrição
Palavras-chave
Fungos fitopatogenicos, Soja - Resistência a doenças e pragas, Soja - Doenças e pragas - Controle, Soybean - chemical control
Como citar
MEYER, Maurício Conrado. Caracterização de Rhizoctonia solani Kühn, agente causal da mela da soja (Glycine max (L.) Merrill), seleção de genótipos e controle químico. 2002. xiii, 126 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Agronômicas, 2002.