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Master's Dissertation
DOI
10.11606/D.11.2002.tde-18072002-145527
Document
Author
Full name
Carolina Leoni Velazco
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2002
Supervisor
Committee
Ghini, Raquel (President)
Fernandes, Nelson Gimenes
Menten, Jose Otavio Machado
Title in Portuguese
Indução de supressividade a Phytophthora nicotianae em mudas de limão cravo com lodo de esgoto.
Keywords in Portuguese
condicionadores do solo
gomose
limão cravo
lodo de esgoto
microbiologia do solo
Abstract in Portuguese
Uma alternativa de manejo das doenças de citros causadas por Phytophthora spp. é o uso de matéria orgânica. Com o objetivo de avaliar os efeitos da incorporação de lodo de esgoto ao solo na indução de supressividade a Phytophthora nicotianae Breda de Haan (1896) em plântulas de limão cravo (Citrus lemonia (L.) Osbeck), foram realizados diversos experimentos em laboratório, casa de vegetação e campo. O aumento nas doses de lodo de esgoto, nos experimentos em laboratório, em casa de vegetação e em campo, resultou na redução do pH e aumento da condutividade elétrica do solo; aumento da atividade microbiana do solo (avaliada pela hidrólise de diacetato de fluoresceina - FDA e pela respiração microbiana); além de uma redução na recuperação de P. nicotianae, tanto do substrato e do solo como das raízes de plântulas e mudas. Em alguns experimentos, a recuperação do patógeno correlacionou-se significativa e negativamente com a atividade microbiana do solo(FDA) e com a condutividade elétrica. Um melhor desenvolvimento de plântulas e mudas foi observado com a incorporação de lodo até 20%. Esses resultados indicam um efeito supressivo do lodo de esgoto a P. nicotianae, nas condições avaliadas, explicado por fatores químicos e biológicos. Dentre os fatores químicos destacam-se o aumento da condutividade elétrica e a inibição do crescimento das colônias do patógeno em meio de cultura com extratos ácidos de lodo. Os fatores biológicos envolveram o aumento da atividade microbiana do solo e a presença de fungos (Aspergillus sp. e Trichoderma sp.) e actinomicetos antagonistas a P. nicotianae.
Title in English
Suppressiviness induction to phytophthora nicotianae on rangpuor lime with sewage sludge.
Keywords in English
citrus gummosis
rangpuor lime
sewage sludge
soil amendments
soil microbiology
Abstract in English
Soil organic matter amendments may provide an alternative for the management of citrus soil diseases caused by Phytophthora spp. The effects of incorporating residential sewage sludge into the soil in order to induce suppressiviness to Phytophthora nicotianae Breda de Haan (1896) in seedlings and plantlets of rangpuor lime (Citrus limonia (L.) Osbeck) were evaluated. For this, several experiments under laboratory, greenhouse and field conditions were conducted. In almost all experiments, while sewage sludge doses enlarged, soil pH values decreased and soil electrical conductivity increased; soil microbial activity (evaluated by the fluorescein diacetate hydrolysis - FDA and microbial respiration) increased, and P. nicotianae recovery from soil and roots tended to decreased. In some experiments, significantly and negative correlations were observed between P. nicotianae recuperation and microbial activity (FDA), and between P. nicotianae recuperation and soil electrical conductivity. Seedlings and plantlets development improved at a maximum of 20% v/v sewage sludge soil incorporation. These results suggest a sewage sludge suppressive effect on P. nicotianae, explained by chemical and biological factors, under the experimental conditions of the tests performed. Among chemical factors, the increase of the soil electrical conductivity and colony growth inhibition of P. nicotianae on culture media amended with an acid sewage sludge extract, were indicated. The biological factors involved in suppressiviness were the increase of soil microbial activity and the presence of fungi (Aspergillus sp. and Trichoderma sp.) and actinomyces antagonistic to P. nicotianae.
 
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Publishing Date
2002-08-07
 
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