Dissertationen zum Thema „Rhizoctonia solani kuhn“

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O trabalho foi realizado nas instalações do Departamento de Produção Vegetal/Defesa Fitossanitária da Faculdade de Ciências Agronômicas-UNESP (22º51’S e 48º26’W)- Botucatu/SP e consistiu da instalação de dois experimentos idênticos em épocas distintas com duas etapas cada. A primeira destas objetivou verificar o efeito da solarização sobre a comunidade nativa de Pseudomonas spp. fluorescentes no campo e em túnel plástico. Nesta fase, monitorou-se a população das bactérias aos 0, 7, 14, 21, 28 e 35 dias durante a solarização. Na segunda etapa, verificou-se a indução de supressividade do solo, no controle da doença, em feijoeiro na cultivar ‘IAC Carioca’, causada por Rhizoctonia solani GA 4 HGI, agente causal do ‘damping-off’ do feijoeiro, através do emprego do solo previamente solarizado ou não, transportado para vasos, sob condições de casa-de-vegetação. Monitorou-se a população das bactérias em meio B de King e o índice de severidade de R. solani aos 7, 14 e 21 dias após a semeadura através de escala de notas. Para a inoculação o fungo foi cultivado em substrato areno-orgânico e incorporado ao solo na proporção de 0,5% p/v. A detecção endofítica ou epífita de Pseudomonas spp. fluorescentes em sementes de feijão, o teste de antagonismo a Rhizoctonia solani e a caracterização genérica através de testes morfológicos e bioquímicos, foram feitos em condições de laboratório. O tempo de solarização foi de 35 dias nos períodos de 19/11/99 a 24/12/99 e de 17/02/00 a 23/03/00. Observou-se maiores temperaturas em túnel plástico nos dois períodos. As maiores médias máximas no campo e túnel plástico foram maiores no primeiro período do que no segundo. A solarização e ausência de cobertura vegetal diminuíram a população das bactérias a níveis indetectáveis no campo e túnel... .
The study was carried out at the Departament of Plant Production - UNESP– Botucatu/SP, Brazil (22º51’S and 48º26’W). The study consisted of two identical experiments installed in different periods with two stages each. The objective of the first experiment was to verify the effect of solarization on the native community of fluorescent Pseudomonas spp. under field and plastic tunnel conditions. The bacterium population was monitored at 0, 7, 14, 21, 28 and 35 days of solarization. In the second experiment, it was verified a possible induction of soil suppressiveness to control disease, caused by Rhyzoctonia solani GA 4 HGI on bean ‘IAC Carioca’, through solarized or not solarized soil transferred to vases, under greenhouse conditions. The bacterium population was monitored in King’s B medium and the severity rate of R. solani was determined at the 7, 14 and 21 days after sowing using a scale of notes. R. solani was cultivated for inoculation in sand-organic substratum and incorporated at the soil in the 0.5 w/v proportion. The detection of the endophytic or epiphytic forms of the fluorescent Pseudomonas spp. in bean seeds, the antagonism test against Rhizoctonia solani and the generic characterization by the morphological and biochemistry tests were made under laboratory conditions. The extension of the solarization was 35 days, from 11/19/00 to 12/24/00 and from 02/17/00 to 03/23/00. The greatest temperatures were observed in plastic tunnel in both periods. The greatest maximum media temperatures were bigger in the first period than in the second one. The soil solarization and the absence of vegetable mulching decreased the bacteria population at undetected levels in the field and tunnel. The soil solarization in the field and tunnel did not induce soil suppressiveness to R. solani. It was not observed endophytic and epiphytic forms of... (Complete abstract, click electronic address below).

Orientador: Nilton Luiz de Souza
Resumo: O trabalho foi realizado nas instalações do Departamento de Produção Vegetal/Defesa Fitossanitária da Faculdade de Ciências Agronômicas-UNESP (22º51'S e 48º26'W)- Botucatu/SP e consistiu da instalação de dois experimentos idênticos em épocas distintas com duas etapas cada. A primeira destas objetivou verificar o efeito da solarização sobre a comunidade nativa de Pseudomonas spp. fluorescentes no campo e em túnel plástico. Nesta fase, monitorou-se a população das bactérias aos 0, 7, 14, 21, 28 e 35 dias durante a solarização. Na segunda etapa, verificou-se a indução de supressividade do solo, no controle da doença, em feijoeiro na cultivar 'IAC Carioca', causada por Rhizoctonia solani GA 4 HGI, agente causal do 'damping-off' do feijoeiro, através do emprego do solo previamente solarizado ou não, transportado para vasos, sob condições de casa-de-vegetação. Monitorou-se a população das bactérias em meio B de King e o índice de severidade de R. solani aos 7, 14 e 21 dias após a semeadura através de escala de notas. Para a inoculação o fungo foi cultivado em substrato areno-orgânico e incorporado ao solo na proporção de 0,5% p/v. A detecção endofítica ou epífita de Pseudomonas spp. fluorescentes em sementes de feijão, o teste de antagonismo a Rhizoctonia solani e a caracterização genérica através de testes morfológicos e bioquímicos, foram feitos em condições de laboratório. O tempo de solarização foi de 35 dias nos períodos de 19/11/99 a 24/12/99 e de 17/02/00 a 23/03/00. Observou-se maiores temperaturas em túnel plástico nos dois períodos. As maiores médias máximas no campo e túnel plástico foram maiores no primeiro período do que no segundo. A solarização e ausência de cobertura vegetal diminuíram a população das bactérias a níveis indetectáveis no campo e túnel... (Resumo completo, clicar acesso eletrônico abaixo).
Abstract: The study was carried out at the Departament of Plant Production - UNESP- Botucatu/SP, Brazil (22º51'S and 48º26'W). The study consisted of two identical experiments installed in different periods with two stages each. The objective of the first experiment was to verify the effect of solarization on the native community of fluorescent Pseudomonas spp. under field and plastic tunnel conditions. The bacterium population was monitored at 0, 7, 14, 21, 28 and 35 days of solarization. In the second experiment, it was verified a possible induction of soil suppressiveness to control disease, caused by Rhyzoctonia solani GA 4 HGI on bean 'IAC Carioca', through solarized or not solarized soil transferred to vases, under greenhouse conditions. The bacterium population was monitored in King's B medium and the severity rate of R. solani was determined at the 7, 14 and 21 days after sowing using a scale of notes. R. solani was cultivated for inoculation in sand-organic substratum and incorporated at the soil in the 0.5 w/v proportion. The detection of the endophytic or epiphytic forms of the fluorescent Pseudomonas spp. in bean seeds, the antagonism test against Rhizoctonia solani and the generic characterization by the morphological and biochemistry tests were made under laboratory conditions. The extension of the solarization was 35 days, from 11/19/00 to 12/24/00 and from 02/17/00 to 03/23/00. The greatest temperatures were observed in plastic tunnel in both periods. The greatest maximum media temperatures were bigger in the first period than in the second one. The soil solarization and the absence of vegetable mulching decreased the bacteria population at undetected levels in the field and tunnel. The soil solarization in the field and tunnel did not induce soil suppressiveness to R. solani. It was not observed endophytic and epiphytic forms of... (Complete abstract, click electronic address below).
Mestre

Soil inoculum density and the incidence of black root rot of cotton caused by Thielaviopsis basicola were monitored in two adjacent fields planted mid-April to Gossypium hirsutum 'Acala 1517' at Duncan, AZ (1160 m elev.). Forty soil cores (3.5 x 15 cm) were taken from the root zone and 80 plants were collected biweekly in the two fields from 5/7/87 to 9/28/87. The inoculum density (cfu/g air-dried soil) was determined by plating soil dilutions onto a selective medium. Disease severity was rated on a scale of 1 (slight cortical decay) to 4 (severe cortical decay). Mean inoculum density in Field 1 soil was 65 cfu/g soil and 20% of the seedlings were infected with a severity rating averaging 1.6. In Field 2 the inoculum density, percentage of infected plants, and disease rating were 225 cfu/g soil, 93, and 3.2, respectively. No cortical decay was noted after June 6 in either field. Yields were similar in both fields. Field and laboratory studies indicate that high disease incidence of black root rot caused by T. basicola results in reduced incidence of seedling disease caused by Rhizoctonia solani. For example, 1 mo after untreated seeds of G. barbadense 'Pima S-6' were planted into a cotton field in Coolidge, AZ with natural inoculum levels of 12 cfu/100 g soil and 225 cfu/g soil of R. solani and T. basicola, respectively, 98% of the plants were infected by T. basicola while only 2% were infected by R. solani. Eleven out of the 12 R. solani propagules were pathogenic to cotton. The same levels of inoculum, were added to autoclaved field soil in growth chambers at 18 C and 5200 lux light in four treatments. The first treatment, T. basicola alone, caused a 98% incidence of black root rot. Rhizoctonia solani alone resulted in a 38% incidence of disease, whereas inoculum of T. basicola and R. solani, together caused a 98% and 17% incidence of disease caused by T. basicola and R. solani, respectively. Simultaneous inoculations of 4-day-old G. hirsutum 'DP 90' seedlings on water agar plates with inoculum of T. basicola and R. solani resulted 5 days later in a significant decrease in infection by R. solani as compared to that in the seedlings inoculated with R. solani only.

碩士
國立中興大學
植物學系
81
Rhizotonia solani is a pathological fungi in the soil. It often causes serious diseases of plants. There are thirteen kinds of Rhizotonia solani strains Kuhn AG-4 in Taiwan. Among them, CHU344 and CHU345 are the only two strains without plasmids. We analyzed the relationship between plasmids and R.solani's necessary growth conditions, pathology and cross protection. In our study of the nutrition ultilization,the thirteen strains can grow using different carbon sources. The eleven which contain plasmids grow favorably in alkaline. They can't grow well when we use glycine as the only nitrogen source.And strains without plas- mids are apt to grow up in neutral conditions but do not grow well using threonine as the only nitrogen source.In the infection tests, learned that CHU344 was the strain with a weak pathology, CHU341 had a stronger pathology, and the others had the strongest pathology. CHU341, CHU344,CHU345,CHU347 and CHU350 showed a cross protection against the strains of strong pathology. Therefore , there may not be a direct relation between plasmids and R. solani's growth conditions and pathology. From the extract of the strain with a cross protection function. We speculate that chiti- nase, which is induced by infection, could be involved in the effect of cross protection. If the plasmid isn' t concerned with pathology, then the plasmid can be used as a vector in fungal genetic techology. Then the re- sult of growth condition tests and cross protection can be used for biological control.

Bibliography: leaves 119-143
v, 148 leaves : ill. ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 2000

碩士
國立虎尾科技大學
生物科技研究所
101
The methanol extracts of the leaves of Peltophorum pterocarpum collected from Vietnam demonstrated the anti-cancer activity in the preliminary pharmacological screening. Therefore, the present research is aimed to identify the constituents of P. pterocarpum and elucidate the relationship between chemical compositions and bioactivity. The methanol extracts were fractionated, and further purified with the assistance of column chromatography to afford 17 compounds. These isolates would be subjected into the bioactivity examinations to explore new natural anti-cancer lead compounds. Rhizoctonia solani Kuhn caused serious damping-off diseases of numerous crops in Taiwan, especially it is a major problem for the commercial production of vegetable seedlings grown in cell-plug systems. In our labs, we continued to focus on the discovery for the plant-derived pesticides against RS AG-4. Among the tested extracts, the methanol extracts of Arctii Fructus did not show any inhibition of the growth of plant pathogenic fungi. However, the indicator compounds in the methanol extracts of Arctii Fructus were transformed to other compounds according to HPLC monitoring. Thus, in the present study the RS AG-4. was used as a biocatalyst and the biotransformation of arctiin was investigated. Conversion of arctiin to arctigenin was achieved by the hydrolysis of sugar moieties. In addition, an anti-inflammatory lignan dimer reported from the Arctii Fructus, diarctigenin was produced in good yield. It would be an excellent method to produce large scale of diarctigenin for the successive medicinal examinations.

碩士
國立屏東科技大學
熱帶農業暨國際合作系所
100
The emergency of several environmental and human threats, brought from the abuse of pesticides in agriculture, has strengthened the search for sustainable strategies to control plant diseases. Suppression of soil-borne diseases observed after soil amendments with Brassica crops, attributed to bioactive compounds from glucosinolate (GSLs) hydrolysis and modifications on soil microbial communities, is currently one of the main sources for developing alternative control methods. In this study, the potential use of three Brassica species, including B. rapa, B. napus and B. juncea, as soil amendments to control Rhizoctonia solani damping-off disease was investigated in vitro and in greenhouse. In vitro, assays included the use of a nutrient-rich and a nutrient-poor medium to evaluate the effect of toxic compound and the nutritional content added with Brassica tissues on the suppression of R. solani hyphal growth (fungi-toxicity). In greenhouse, the incidence of damping-off disease was evaluated in cabbage (Brassica oleracea L. var. capitata) seedlings growing in three soil sources amended with dry Brassica tissues. The impact of Brassica amendments on soil reaction, seedling growth and microbial dynamics were also evaluated in order to elucidate possible mechanisms involved in disease reduction. Fungi-toxicity tested in the nutrient-rich medium demonstrated that tissues from all three Brassica species released fungi-toxic compound against R. solani hyphal growth. However, results in the nutrient-poor medium with water soluble extracts from Brassica tissues, indicated that nutritional content in the tissues can reduce fungi-toxicity, which may negatively influence the efficiency of bio-fumigation after field application. Moreover, greenhouse bioassays demonstrated that Brassica amendments strongly impact on microbial population, while disease suppression was not consistent with fungi-toxicity observed in vitro. Volatile compounds released by B. juncea demonstrated to be highly toxic to the growth of R. solani (98.2-100 % hyphal inhibition) in vitro; however, disease suppression by this specie observed in greenhouse varied with soils sources. On the other hand, B. rapa and B. napus revealed steady reduction of disease incidence along three different soils (< 13.3 % incidence, similar to non-diseased soil), which could partially be explained by the higher fungi-toxicity of compounds in their water soluble extractions, than those of B. juncea. Nevertheless, disease incidence on Brassica amended soils were strongly related with the ratio between actinomycetes and fungi populations, showing that at ratios higher than 350, disease incidence was not significant. Populations of actinomycetes higher than 12.2 x 105 CFU x g-1, and fungi lower than 9.1 x 103 CFU x g-1, were also related with disease suppression in some soils, but in a moderated way. The high correlation found between soil microbial community and disease control strongly supported the hypothesis that microbial modification after Brassica amendments is the main mechanism involved in disease suppression in the long term. In addition, soil reaction was similarly affected by amendments regardless Brassica specie, suggesting that released products from Brassica tissues may act as a buffer in soil determining to a specific soil reaction. However, resulting soil reaction didn’t show relationship with disease suppression or the dynamics of soil microorganisms. Similarly, seedling growth was slightly reduced followed by amendments regardless Brassica specie, which suggested that GSL hydrolysis products could possess phytotoxic activity, or that Brassica amendment could have promoted the population of phytotoxic bacteria. Stable results in disease control and microbial community modification suggest significant potential of using B. rapa (first option) and B. napus (second option) for controlling R. solani damping-off disease in field. However, the optimization of Brassica amendment in field for different target crops must be further evaluated to ensure its efficacy in different agrosystems.