Made available in DSpace on 2016-04-28T14:57:35Z (GMT). No. of bitstreams: 1
Ana Rosa de Figueiredo Fernandes.pdf: 5291957 bytes, checksum: e9ba6c76361eb4a2e901846a5bb5c2dd (MD5)
Previous issue date: 2009-10-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / ?The pathogenicity of Pratylenchus brachyurus on tobacco (Nicotiana tabacum) cultivar K326
was evaluated in experiments testing different initial population densities of the nematode (Pi
= 0; 1,000; 3,000; 9,000 and 27,000 eggs and larvae per plant), in eight replications. The
isolate was monoxenically multiplied on carrot discs. At the end of the experiment (70 days
after inoculation), the above ground part of each plant was weighed and measured and, the
respective root system was processed. The reproduction rate of Pratylenchus brachyurus was
estimated by extracting the nematodes of the roots and of the soil. Necroses on the roots of the
tobacco plants were observed. Pratylenchus brachyurus caused well-delimited root lesions on
tobacco root. None of the analyzed plants died; however plant growth was reduced. Also, it
was observed a decrease of the fresh mass of roots and of the dry top weight, mainly under the
highest population density (27,000 nematodes per plant). The reproduction rate was low.
Besides the interaction between Pratylenchus brachyurus and Ralstonia solanacearum in two
tobacco varieties, Virg?nia K326 and Burley By21 was evaluated. Test plants were inoculated
with the nematode in the initial population density of 3,000 individuals (eggs and larvae) by
plant and, 15 days later, the plants were inoculated with a sample of soil infested by the bacterium, in estimated population density of 106 CFU.g-1 of soil. Besides the mixed
inoculation with Pratylenchus brachyurus and Ralstonia solanacearum, tobacco plants were
single inoculated. The plants were monitored daily. Dates of the beginning of symptom
expression were registered, as well as symptom evolution. When the plants were inoculated
with Pratylenchus brachyurus and Ralstonia solanacearum, symptom of wilt that is caused
by the bacterium Ralstonia solanacearum began earlier than in single inoculated plants, and
they also evolved quicker, inclusive in the variety Virg?nia K326 that was considered more
tolerant. In this case, the presence of Pratylenchus brachyurus, in the root system of these
plants, probably favored the infection by Ralstonia solanacearum, even before the symptoms
caused by the nematodes could be detected. This study was done in greenhouse and under
laboratory conditions. / ?A patogenicidade de Pratylenchus brachyurus em fumo Virg?nia K326 foi avaliada em
experimento no qual foram testadas diferentes densidades populacionais iniciais do nemat?ide
(Pi = 0; 1.000; 3.000; 9.000 e 27.000 ovos e larvas por planta), em oito repeti??es. O isolado
foi multiplicado axenicamente em discos de cenoura. Ao final do experimento (85 dias), as
plantas tiveram sua parte a?rea pesada e medida e foi processado o sistema radicular de cada
uma. O fator de reprodu??o foi estimado por extra??o dos nemat?ides das ra?zes e do solo.
Necroses nas ra?zes das plantas foram observadas. Pratylenchus brachyurus causou les?es
radiculares delimitadas nas ra?zes de fumo. N?o houve morte de nenhuma planta analisada,
por?m a altura das plantas foi afetada e tamb?m a massa seca da parte a?rea, principalmente
sob a densidade populacional mais alta, de 27.000 nemat?ides por planta. O fator de
reprodu??o foi baixo. Al?m disto, avaliou-se a intera??o entre Pratylenchus brachyurus e
Ralstonia solanacearum em fumo Virg?nia variedade K326 e fumo Burley variedade BY21.
As plantas foram inicialmente inoculadas com o nemat?ide na densidade populacional de
3.000 ovos e larvas por planta e 15 dias ap?s, foram inoculadas com uma amostra de solo infestado pela bact?ria, na densidade populacional estimada de 106 UFC.g-1 de solo. Al?m da
inocula??o mista com Pratylenchus brachyurus e Ralstonia solanacearum, testemunhas
foram inoculadas isoladamente. As plantas foram monitoradas diariamente, anotando-se a
data de in?cio e da evolu??o dos sintomas. Quando as plantas foram inoculadas com os
Pratylenchus brachyurus e Ralstonia solanacearum, os sintomas de murcha, que s?o
causados pela bact?ria se manifestaram mais cedo e tamb?m evolu?ram mais r?pido, inclusive
na variedade K326 que foi considerada mais tolerante. Neste caso, provavelmente a presen?a
de Pratylenchus brachyurus, no sistema radicular dessas plantas, favoreceu a infec??o por
Ralstonia solanacearum, antes mesmo que os sintomas causados pelo nemat?ide pudessem
ser observados. Este trabalho foi realizado em casa de vegeta??o e em laborat?rio.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:tede/503 |
| Date | 29 October 2009 |
| Creators | Fernandes, Ana Rosa de Figueredo |
| Contributors | Pimentel, Joao Pedro |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Curso de P?s-Gradua??o em Fitossanidade e Biotecnologia Aplicada, UFRRJ, Brasil, Entomologia Aplicada |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFRRJ, instname:Universidade Federal Rural do Rio de Janeiro, instacron:UFRRJ |
| Rights | info:eu-repo/semantics/openAccess |
Page generated in 0.0028 seconds