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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1984.tde-20220207-205943
Document
Author
Full name
Herberte Pereira da Silva
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1983
Supervisor
 
Title in Portuguese
Herança da resistência a antracnose foliar em milho (Zea mays L.) e métodos de avaliação
Keywords in Portuguese
ANTRACNOSE FOLIAR
FUNGOS FITOPATOGÊNICOS
HERANÇA GENÉTICA
MILHO
RESISTÊNCIA À DOENÇA
Abstract in Portuguese
A resistência genética e, sem dúvida, um método eficiente e econômico de controle das doenças do milho. No presente trabalho, foram utilizadas 6 linhagens enctogâmicas de milho, para o estudo da herança da resistência à antracnose foliar e para a comparação de dois métodos de avaliação: tipo de lesão e porcentagem da nervura central afetada. As linhagens e as respectivas gerações F1, F2, RCP1, e RCP2, obtidas dos cruzamentos das linhagens 51, 1, 46, 171 e 96 com a linhagem 91 altamente suscetível foram inoculadas através da pulverização de cerca de 4 ml da suspensão de esporos na concentração 5,0 x 105 esporos/ml, no cartucho de cada planta. As seis linhagens endogâmicas foram avaliadas através de dois métodos, o primeiro se baseou no tipo de lesão observada na folha, 15 dias apôs a primeira inoculação, enquanto que o segundo método se baseou numa estimativa visual da porcentagem da nervura central afetada, 15 dias após a constatação do florescimento em 50% das plantas. Os resultados obtidos demonstram que as linhagens estudadas se comportaram diferentemente em relação ao método utilizado, especificamente as linhagens 46 e 171, as quais apresentam reação intermediária quando avaliadas com base no tipo de lesão e resistentes com base na porcentagem da nervura central afetada. Os estudos da herança da resistência a queima do limbo foliar e a infecção natural na nervura central para 5 linhagens endogâmicas revelaram que a resistência e devida aos genes na condição dominante e os efeitos genéticos aditivos assumiam importância primária em todas as famílias. As estimativas da herdabilidade no sentido amplo para as duas formas de manifestação da doença eram altas, sendo que a resistência a infecção do limbo foliar e governada por 1 a 4 genes dominantes e a resistência â infecção natural na nervura central por 1 a 2 genes dominantes. Em vista dos resultados obtidos, a seleção mas sal deverá fornecer rápido progresso no melhoramento para obtenção de populações de milho resistentes, além disso os métodos genealógico e de retrocruzamento podem ser eficientes na obtenção de linhagens resistentes.
 
Title in English
Inheritance of resistance to anthracnose foliar in corn ( L.) and methods of evaluation
Abstract in English
Genetic resistance i s an efficient and economic method used for controlling diseases of corn. Six inbred lines were used for studying the inheritance of resistance to Colletotrihum graminicola in maize leaves, the resistance being evaluated on the basis of the lesion type and on the percentage of infection in the central vein. The inbred lines and their respective F1, F2, BCP1 and BCP2 generations, produced by crossing of the inbred lines 51, 1, 46, 171 and 96 with the highly susceptible inbred line 91, were inoculated by spraying approximately 4 ml of a spore suspension, at a concentration of 5.0 x 105 spores/ml, into the leaf whorl of the plants. The six inbred lines were rated on the basis of the lesion type observed on the leaves 15 days after the first inoculation, as well as on a visual estimate of the percent infection on the central vein 15 days after midsilk. The results obtained revealed that the inbred lines reacted differently in relation to the caracters evaluated. Inbred lines 46 and 171, which were rated as intermediately resistant on the basis of the lesion type were considered resistant when evaluated on the based of the percentage of the infected tissue of the central vein. The inheritance of resistance to anthracnose, based on the lesion type and on the percentage of infected tissue of the central vein, revealed that the resistance was conditioned by genes in a dominant condition, and that the additive genetic effects were of primary importance in all families studied. Estimates of broad-sense heritability for the two forros of disease manifestation were high. The resistance to foliar infection being controlled by 1 to 4 dominant genes, whereas the resistance to central leaf vein was controlled by 1 to 2 dominant genes. Mass selection should gi ve a rapid progress in the improvement of resistant corn populations, and pedigree selection and backcross breeding should be efficient ways to obtain resistant inbred lines.
 
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Publishing Date
2022-02-07
 
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