Seleção de genótipos de milho quanto à eficiência no uso de Azospirillum brasilense
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Data
2019-11-29
Autores
Silva, Flávia Alves Marques da [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O uso de Azospirillum brasilense na agricultura vem promovendo benefícios em termos ambientais, econômicos e no desempenho de algumas culturas. Assim, o objetivo desta pesquisa, consiste em identificar e selecionar genótipos de milho eficientes no uso de A. brasilense. Para isso, foram avaliados 66 genótipos de milho, nos anos de 2017 e 2018, no período de segunda safra, com dois experimentos em cada ano. Os experimentos foram conduzidos de forma similar, porém com coberturas diferentes, sendo no experimento 1 aplicado nitrogênio na forma de ureia e no experimento 2 inoculação com A. brasilense. O delineamento experimental foi de blocos ao acaso com quatro repetições de cada tratamento e parcelas que representavam uma população de 60.000 plantas∙ha-1. Com a informação de ambos os experimentos, foram calculadas as eficiências no uso de A. brasilense para altura de planta, altura de espiga, produtividade, prolificidade e porcentagem de plantas em pé. A produtividade, do experimento com inoculação de A. brasilense e a eficiência no uso de A. brasilense para produtividade foram submetidos a uma análise de variância, um teste de comparação de médias e uma classificação por método de gráfico de quadrantes. Essas análises possibilitaram a seleção de 13 genótipos responsivos e eficientes no uso de A. brasilense. Por meio dos resultados, foi possível ainda validar as técnicas de seleção empregadas. As eficiências de todos os caracteres foram submetidas à análise dialélica, a qual apresentou resultados indicando tanto a presença de genes de ação aditiva como dominante entre as eficiências no uso de A. brasilense avaliadas. Também foi possível selecionar um parental com maior concentração de alelos favoráveis para mais de uma eficiência, e quatro cruzamentos, com boa complementariedade para mais de uma eficiência e presença de pelo menos um parental com alta concentração de alelos favoráveis. A pesquisa contribuiu para o avanço de programas de melhoramento de milho voltados ao uso de Azospirillum brasilense, tanto como fonte de germoplasmas quanto em relação eficácia dos métodos de caracterização e seleção de genótipos.
The use of Azospirillum brasilense in agriculture has been promoting environmental, economic and performance benefits of some crops. Thus, the aim of this research is to identify and select maize genotypes use efficient for A. brasilense. To do this, 66 maize genotypes were evaluated in 2017 and 2018 during the second season, with two experiments each year. The experiments were conducted ina similar way, but with different top-dressing, being applied in experiment 1 nitrogen in the form of urea and in experiment 2 inoculation with A. brasilense. The experimental design was randomized block design with four replications of each treatment and plot representing a population of 60.000 plants∙ha1 . With the information from both experiments were calculated the use efficiency of A. brasilense for plant height, ear height, yield, prolificacy and percentage of standing plants. The yield of the A. brasilense inoculation experiment and the use efficiency of A. brasilense for yield were submitted to a variance analysis, a mean comparison test and a quadrant plot method of classification. The result of these analyzes allowed the selection of thirteen responsive and use efficient genotypes for A. brasilense. Through the results, it was also possible to validate the selection tecniques employed. The efficiencies of all characters were submitted to diallel analysis, which showed results indicating the presence of both, additive and dominant, action genes among the evaluated efficiencies. It was also possible to select one parent with higher concentration of favorable alleles for more than one efficiency, and four crosses with good complementarity, for more than one efficiency, and the presence of at least one parent with high concentration of favorable alleles. The research contributed to the advancement of maize breeding programs aimed at the use of Azospirillum brasilense, such as a source of germplasm as in relation to the efficacy of genotype characterization and selection methods. Keywords: diallel analysis, diazotrophic bacteria, yield, Zea mays L
The use of Azospirillum brasilense in agriculture has been promoting environmental, economic and performance benefits of some crops. Thus, the aim of this research is to identify and select maize genotypes use efficient for A. brasilense. To do this, 66 maize genotypes were evaluated in 2017 and 2018 during the second season, with two experiments each year. The experiments were conducted ina similar way, but with different top-dressing, being applied in experiment 1 nitrogen in the form of urea and in experiment 2 inoculation with A. brasilense. The experimental design was randomized block design with four replications of each treatment and plot representing a population of 60.000 plants∙ha1 . With the information from both experiments were calculated the use efficiency of A. brasilense for plant height, ear height, yield, prolificacy and percentage of standing plants. The yield of the A. brasilense inoculation experiment and the use efficiency of A. brasilense for yield were submitted to a variance analysis, a mean comparison test and a quadrant plot method of classification. The result of these analyzes allowed the selection of thirteen responsive and use efficient genotypes for A. brasilense. Through the results, it was also possible to validate the selection tecniques employed. The efficiencies of all characters were submitted to diallel analysis, which showed results indicating the presence of both, additive and dominant, action genes among the evaluated efficiencies. It was also possible to select one parent with higher concentration of favorable alleles for more than one efficiency, and four crosses with good complementarity, for more than one efficiency, and the presence of at least one parent with high concentration of favorable alleles. The research contributed to the advancement of maize breeding programs aimed at the use of Azospirillum brasilense, such as a source of germplasm as in relation to the efficacy of genotype characterization and selection methods. Keywords: diallel analysis, diazotrophic bacteria, yield, Zea mays L
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análise dialélica, bactérias diazotróficas, produtividade, Zea mays L.