Reação de genótipos de milho à mancha ocular e caracterização do agente causal
This investigation on corn eyespot was based on its causal agent and on the preparation of a diagrammatic scale that helped evaluate the reaction of corn genotypes, in correlation with the response obtained from the plant’s biochemical defenses. In the first step of the study, 35 Kabatiella zeae iso...
| Autor principal: | Camochena, Rubia Cristiani |
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| Formato: | Dissertação |
| Idioma: | Português |
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Universidade Tecnológica Federal do Paraná
2012
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riut-1-2702015-03-07T06:04:18Z Reação de genótipos de milho à mancha ocular e caracterização do agente causal Camochena, Rubia Cristiani Santos, Idalmir dos Milho - Cultivo Milho - Melhoramento genético Corn - Planting Corn - Breeding This investigation on corn eyespot was based on its causal agent and on the preparation of a diagrammatic scale that helped evaluate the reaction of corn genotypes, in correlation with the response obtained from the plant’s biochemical defenses. In the first step of the study, 35 Kabatiella zeae isolates from different corn genetic materials had their colonies evaluated for color and aspect, and their spores measured in PSA medium. The following culture media were used: PSA (potato, sucrose, agar), MA (malt and agar), OA (oat and agar) and CA (corn flour and agar). Disks (5 mm in diameter) were placed in the center of Petri dishes containing the respective culture media. The dishes were incubated at 24°C and a 12-hour photoperiod for 10 days. Colony traits and conidia measurements were evaluated in PSA, while radial growth was evaluated in the four media. There were differences between all isolates with regard to the culture media. Spore size varied from 3-4 × 27-33 μm in width and length, respectively, and 80% of the isolates had a light color (pink) and a coriaceous and wrinkled aspect; the highest mycelial growth was observed in the PSA medium. A diagrammatic scale was developed by randomly collecting 110 diseased leaves in the field, discarding 20 cm from the leaf tip, and using the next 20 cm. Measurements were made for leaf area and the area containing lesions in order to determine minimum and maximum severity limits of the disease; intermediate levels were calculated mathematically. The severity levels observed in the field followed logarithmic increases, representing: 0.9; 2.0; 4.0; 9.0; 18.0; 32.0; and 51.0% of leaf area with lesions. Scale validation consisted of two steps: in the first, 10 evaluators experienced in plant disease evaluations assessed 30 leaves with different severity levels, both using and not using the diagrammatic scale. In the second step, another 10 naive (without experience) evaluators performed the same evaluations, both using and not using the diagrammatic scale. Actual and estimated severity values were compared by linear regression, and evaluator accuracy and precision were analyzed. Better accuracy and precision were obtained for visual estimates made with the diagrammatic scale. The reaction of corn genotypes to eyespot was evaluated in the city of Pato Branco-PR during the 2006/2007 growing season using 33 hybrids, and during the 2007/2008 growing season using 10 hybrids at two distinct sowing seasons, and in the city of Palma Sola-SC during the 2007/2008 growing season with 8 hybrids. Hybrids AG 9020 and SPRINT were the most susceptible to the disease in relation to AS 1565 and DKB 234; this behavior was observed in both years and planting seasons. The peroxidase enzyme was observed at higher concentrations in leaves of corn hybrids with the lowest eyespot severity. A investigação da mancha ocular do milho foi baseada no seu agente causal e na elaboração de uma escala diagramática da doença que auxiliou na avaliação da sensibilidade dos genótipos de milho, correlacionada com a resposta de defesas bioquímicas da planta. Na primeira etapa do trabalho, 35 isolados de Kabatiella zeae, de diferentes materiais genéticos de milho, foram avaliados quanto à coloração e aspecto das colônias e mensuração dos esporos do fungo em BSA. Os meios de cultura utilizados foram BSA (batata, sacarose e ágar), MA (malte e ágar), AvA (aveia e ágar) e FA (fubá de milho e ágar). Discos de 5 mm de diâmetro, foram colocadas no centro das placas contendo os respectivos meios de cultura. As placas foram incubadas a 24° C com fotoperíodo de 12 horas , por 10 dias. As características das colônias e mensuração dos conídios foram avaliadas em BSA, e o crescimento radial, nos quatro meios. Houve diferença entre todos os isolados em relação aos meios de cultura. Observou-se que a dimensão dos esporos variou de 3- 4 x 27-33 μm, de largura e comprimento, respectivamente, e que 80% dos isolados apresentaram coloração clara (rosa) e aspecto coreáceo e enrugado, e o maior crescimento micelial foi observado no meio BSA. A escala diagramática foi desenvolvida coletando-se 110 folhas doentes, aleatoriamente no campo, eliminando-se 20 cm da extremidade, sendo utilizados os 20 cm seguintes. Foi mensurada a área foliar e área das lesões para determinação dos limites de severidade mínima e máxima da doença, e os níveis intermediários calculados matematicamente. Os níveis de severidade observados em campo seguiram incrementos logarítmicos, representando: 0,9; 2,0; 4,0; 9,0; 18,0; 32,0 e 51,0% da área foliar lesionada. A validação da escala consistiu-se em duas etapas: na primeira, 10 avaliadores, com experiência na avaliação de doenças em plantas, avaliaram 30 folhas com diferentes níveis de severidade, com e sem o uso da escala diagramática. Na segunda etapa, outros 10 avaliadores, sem experiência, fizeram as mesmas avaliações, com e sem uso da escala diagramática. Por meio de regressão linear, foram confrontados valores de severidade reais e estimados, sendo analisadas a acurácia e a precisão dos avaliadores. Constatou-se melhora na acurácia e na precisão das estimativas visuais efetuadas com o auxílio da escala diagramática. A reação de genótipos de milho à mancha ocular foi avaliada no município de Pato Branco-PR na safra 2006/2007, com 33 híbridos e na safra 2007/2008, com 10 híbridos em duas épocas de semeadura e no município de Palma Sola-SC, na safra 2007/2008 com 8 híbridos. Os híbridos AG 9020 e SPRINT apresentaram maior suscetibilidade à doença, em relação à AS 1565 e DKB 234, repetindo este comportamento nos dois locais e épocas de cultivo. A enzima peroxidase foi observada em maior concentração nas folhas dos híbridos de milho com menor severidade de mancha ocular. 2012-06-05T19:43:20Z 2012-06-05T19:43:20Z 2009-02-06 masterThesis CAMOCHENA, Rubia Cristiani. Reação de genótipos de milho à mancha ocular e caracterização do agente causal. 2009. 66 f. Dissertação (Mestrado em Agronomia) - Universidade Tecnológica Federal do Paraná, Pato Branco, 2009. http://repositorio.utfpr.edu.br/jspui/handle/1/270 por application/pdf Universidade Tecnológica Federal do Paraná Pato Branco Programa de Pós-Graduação em Agronomia |
| institution |
Universidade Tecnológica Federal do Paraná |
| collection |
RIUT |
| language |
Português |
| topic |
Milho - Cultivo Milho - Melhoramento genético Corn - Planting Corn - Breeding |
| spellingShingle |
Milho - Cultivo Milho - Melhoramento genético Corn - Planting Corn - Breeding Camochena, Rubia Cristiani Reação de genótipos de milho à mancha ocular e caracterização do agente causal |
| description |
This investigation on corn eyespot was based on its causal agent and on the preparation of a diagrammatic scale that helped evaluate the reaction of corn genotypes, in correlation with the response obtained from the plant’s biochemical defenses. In the first step of the study, 35 Kabatiella zeae isolates from different corn genetic materials had their colonies evaluated for color and aspect, and their spores measured in PSA medium. The following culture media were used: PSA (potato, sucrose, agar), MA (malt and agar), OA (oat and agar) and CA (corn flour and agar). Disks (5 mm in diameter) were placed in the center of Petri dishes containing the respective culture media. The dishes were incubated at 24°C and a 12-hour photoperiod for 10 days. Colony traits and conidia measurements were evaluated in PSA, while radial growth was evaluated in the four media. There were differences between all isolates with regard to the culture media. Spore size varied from 3-4 × 27-33 μm in width and length, respectively, and 80% of the isolates had a light color (pink) and a coriaceous and wrinkled aspect; the highest mycelial growth was observed in the PSA medium. A diagrammatic scale was developed by randomly collecting 110 diseased leaves in the field, discarding 20 cm from the leaf tip, and using the next 20 cm. Measurements were made for leaf area and the area containing lesions in order to determine minimum and maximum severity limits of the disease; intermediate levels were calculated mathematically. The severity levels observed in the field followed logarithmic increases, representing: 0.9; 2.0; 4.0; 9.0; 18.0; 32.0; and 51.0% of leaf area with lesions. Scale validation consisted of two steps: in the first, 10 evaluators experienced in plant disease evaluations assessed 30 leaves with different severity levels, both using and not using the diagrammatic scale. In the second step, another 10 naive (without experience) evaluators performed the same evaluations, both using and not using the diagrammatic scale. Actual and estimated severity values were compared by linear regression, and evaluator accuracy and precision were analyzed. Better accuracy and precision were obtained for visual estimates made with the diagrammatic scale. The reaction of corn genotypes to eyespot was evaluated in the city of Pato Branco-PR during the 2006/2007 growing season using 33 hybrids, and during the 2007/2008 growing season using 10 hybrids at two distinct sowing seasons, and in the city of Palma Sola-SC during the 2007/2008 growing season with 8 hybrids. Hybrids AG 9020 and SPRINT were the most susceptible to the disease in relation to AS 1565 and DKB 234; this behavior was observed in both years and planting seasons. The peroxidase enzyme was observed at higher concentrations in leaves of corn hybrids with the lowest eyespot severity. |
| format |
Dissertação |
| author |
Camochena, Rubia Cristiani |
| author_sort |
Camochena, Rubia Cristiani |
| title |
Reação de genótipos de milho à mancha ocular e caracterização do agente causal |
| title_short |
Reação de genótipos de milho à mancha ocular e caracterização do agente causal |
| title_full |
Reação de genótipos de milho à mancha ocular e caracterização do agente causal |
| title_fullStr |
Reação de genótipos de milho à mancha ocular e caracterização do agente causal |
| title_full_unstemmed |
Reação de genótipos de milho à mancha ocular e caracterização do agente causal |
| title_sort |
reação de genótipos de milho à mancha ocular e caracterização do agente causal |
| publisher |
Universidade Tecnológica Federal do Paraná |
| publishDate |
2012 |
| citation |
CAMOCHENA, Rubia Cristiani. Reação de genótipos de milho à mancha ocular e caracterização do agente causal. 2009. 66 f. Dissertação (Mestrado em Agronomia) - Universidade Tecnológica Federal do Paraná, Pato Branco, 2009. |
| url |
http://repositorio.utfpr.edu.br/jspui/handle/1/270 |
| _version_ |
1805296588091817984 |
| score |
10,814766 |