Colonização de Acidovorax avenae subsp. citrulli em meloeiro e sobrevivência em restos de cultura e no solo

• Ano de defesa: 2008
• Autor(a) principal: OLIVEIRA, Aldenir de
• Orientador(a): SILVEIRA, Elineide Barbosa da
• Banca de defesa: GOMES, Andréa Maria André, LARANJEIRA, Delson, MARIANO, Rosa de Lima Ramos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal Rural de Pernambuco
• Programa de Pós-Graduação: Programa de Pós-Graduação em Fitopatologia
• Departamento: Departamento de Agronomia
• País: Brasil
• Palavras-chave em Português: Cucumis melo; Mancha-aquosa; Ecologia; Colonização; Sobrevivência; Solo; Bacterial fruit blotch; Ecology; Colonization; soil; Melão; Fitopatologia
• Área do conhecimento CNPq: FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6397

This dissertation aimed to study: colonization of Acidovorax avenae subsp. citrulli in melons after inoculation of the first pair of true leaves, seeds and hermaphrodite flowers; bacterial survival in fruit and leaf residues incorporated to the soil at 0, 5, 10 and 15 cm depth and in soils without the host plant, under the influence of different soil type, temperature (10, 15, 20, 25, 30 and 35ºC) and humidity (50 and 100% of field capacity). In all studies a mutant resistant to 100 ppm of rifampicin (Aac1Rif) was utilized. Bacterial colonization was detected until 30 days after inoculation in the 10th pair of true leaves, with populations of 3.1 log UFC g-1 of leaf. In the same period, the shoot segment between the 10th and 11th leaf pair showed population of 3.52 log UFC g-1 of shoot. After seed inoculation the pathogen colonized the hypocotyl, roots, cotyledonary leaves, true leaves and shoots, until reach undetectable levels at 27 days after inoculation. Flower colonization by the bacteria was not verified. Aac1Rif was found in fruit and leaf residues at 0, 5 and 10 cm during 21 days and at 15 cm during 14 days. Highest population relative extinction rates (TERP)were presented by fruits on soil surface [0.1464 log (UFC) day -1] and on leaves at 10cm [0.084 log (UFC) day -1]. Aac1Rif survived on seven soil types only during three days and the soil C showed the highest TERP [0.9062 log (UFC) day-1]. Higher concentrations of Na+ and silt as well as higher populations of actinomycetes and Trichoderma correlated to faster extinction of Aac1Rif populations in soil. Generally for all soils the lowers TERP were found at 10 or 15ºC and the higher, at 30 or 35ºC. There was no significant (P=0.05) interaction between soil and humidity, however the T test showed significant difference (P=0.05) between the TERP at 100% [0.6685 log (UFC) day -1] and 50% [0.504591 log (UFC) day -1] of field capacity. Independent of temperature and humidity, Aac1Rif also survived in soil only during three days.