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Dissertação
Incorporação de fabáceas ao substrato de plantio para controle da podridão-de-escleródio (Sclerotium rolfsii Sacc.) em cubiu (Solanum sessiliflorum Dunal)
Cubiu (Solanum sessiliflorum Dunal) cultivation in the Amazonas state is limited by the high incidence of southern blight caused by the soilborne fungus Sclerotium rolfsii Sacc. The incorporation of plant material into the substrate changes the microflora present by increasing the organic matter...
Autor principal: | Laborda, Laysa de Paiva |
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Grau: | Dissertação |
Idioma: | por |
Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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Assuntos: | |
Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/5308 http://lattes.cnpq.br/4541064238214868 |
Resumo: |
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Cubiu (Solanum sessiliflorum Dunal) cultivation in the Amazonas state is limited by the high
incidence of southern blight caused by the soilborne fungus Sclerotium rolfsii Sacc. The
incorporation of plant material into the substrate changes the microflora present by increasing
the organic matter content and by the plants decomposition exudates, which may be toxic or
beneficial to the different microorganisms present on the substrate. The incorporated organic
matter also increases the nutrient content available to the plant. The objective of this study
was to evaluate the potential for control of southern blight by the incorporation of fresh
comminuted biomass of four Fabaceae species: Erythrina fusca and Senna reticulata, native
to Amazonia, and Desmodium heterocarpon and Gliricidia sepium, exotic to the substrate.
The isolate of S. rolfsii was obtained from cubiu plants with disease symptoms and multiplied
in autoclaved rice. Infestation of the substrate (argisol: chicken manure, 2: 1) was done with
the incorporation of 10 g of colonized rice.L-1, in pots filled with 8 L of substrate, kept in a
nursery. After 20 days of infestation, were incorporated 40 g of the Fabaceae biomass.L-1
substrate. The cubiu seedlings, 90 days after sowing, were transplanted one week after the
incorporation of the Fabaceae. The experimental design was completely randomized, with
three replicates and seven treatments: four species of Fabaceae and three controls, without the
incorporation of biomass. In one control the substrate was not infested and in other, the
plants were sprayed (9 mL.plant-1) twice, 50 days apart, with fungicide (Viper 700®, methyl
thiophanate, 0.49 g a.i. for litter of water). Another experiment was carried out to evaluate the
effect of doses of G. sepium incorporated into the substrate. The experiment had a completely
randomized design and three replicates, with six treatments: incorporation of 40, 80, 120 and
160 g of G. sepium.L-1 substrate and two controls without incorporation of G. sepium. In one
control, the plants were treated with fungicide. In this experiment, the pots were filled with 6
L of substrate infested as described in the previous experiment. In both experiments the
disease and the inoculum incidence in the substrate were evaluated. In the first experiment,
the data from the area below the disease progress curve were submitted to ANOVA and the
means, compared by the Tukey test. In the second experiment, the data were submitted to
regression analysis. In the first experiment the cubiu plants cultived in substrate with
Fabaceae incorporation or treated with fungicide had the same southern blight incidence and
in the pathogen suppression. In the second experiment, the incidence of southern blight was
proportional to the G. sepium dose incorporated. With the incorporation of 139 g of G.
sepium.L-1 no diseased plants were observed. Also the incorporation of 142 g G. sepium.L-1
substrate reduced the population of S. rolfsii in the substrate by 20%. |