Efeito da adubação nitrogenada e inoculação com Azospirillum brasilense em caracteres agronômicos de genótipos de milho
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Data
2018-08-03
Autores
Bertasello, Luiz Eduardo Tilhaqui
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Universidade Estadual Paulista (Unesp)
Resumo
O milho apresenta grande demanda de nitrogênio, sendo interessante a busca de alternativas de maior sustentabilidade econômica e ambiental. Como a utilização da inoculação com bactérias do gênero Azospirillum, capazes de realizarem a fixação biológica de nitrogênio e a produção de hormônios de crescimento. Objetivou-se avaliar e caracterizar o desempenho agronômico de genótipos de milho submetidos a diferentes fornecimentos de nitrogênio (químico e biológico). O experimento foi conduzido na primeira safra 2017/2018 (safra de verão) e segunda safra 2017 (safrinha) em Jaboticabal-SP, utilizando-se 48 genótipos de milho em um delineamento experimental de blocos casualizados com duas repetições, aplicando-se: 1º) 140 kg.ha-1 de nitrogênio via ureia em cobertura, como forma de adubação química; 2º) inoculação de Azospirillum brasilense, em dose de 600 mL.ha-1 via solo, como forma de adubação biológica. Avaliou-se a produtividade de grãos, número de dias para florescimento masculino e feminino, altura de plantas, altura de espigas, acamamento, quebramento, incidência de enfezamento e Fusarium spp. Os dados foram submetidos à análise de variância (Teste F), as médias comparadas pelo teste de Scott-Knott e foi realizada análise estatística multivariada por componentes principais. Observou-se efeito significativo da inoculação com Azospirillum brasilense via solo para altura de plantas, altura de espigas e interação genótipo vs fornecimento de N com menor incidência para Fusarium spp, bem como o aumento de produtividade de grãos em ambas as safras. Foram identificados genótipos responsivos a inoculação, mesmo não apresentando valores superiores à produtividade de grãos frente à adubação nitrogenada de cobertura. A produtividade foi mantida apenas com o uso de Azospirillum brasilense com maior evidência na segunda safra, sendo sua resposta variável em cada genótipo. Tornando-se interessante a continuidade da pesquisa direcionando programas de melhoramento com intuito de selecionar genótipos responsivos à inoculação.
Maize needs high amounts of nitrogen, for this it is interesting to search alternative methods that promote greater economic and environmental sustainability. As the use of inoculation with bacteria of the genus Azospirillum, able to perform the biological fixation of nitrogen and the production of growth hormones. The aim was to evaluate and characterize the agronomic performance of maize genotypes submitted different treatments for nitrogen supply (chemical and biological). The experiment was carried out in 2017 in first crop 2017/2018 and second crop 2017 in Jaboticabal-SP, using 48 maize genotypes in a randomized block design with two replicates as follows: 1) 140 kg.ha-¹ of nitrogen via urea in the cover, as chemical fertilization 2) Azospirillum brasilense inoculation at concentration of 600 mL.ha- ¹ via soil, as biological fertilization. The evaluated traits were: grain yield, male and female flowering, plant height, ear height, lodging, stalk breakage, stunt incidence, and Fusarium spp. Data were submitted to analysis of variance (Test F), the means by the Scott-Knott test and multivariate statistical analysis was performed by principal components. We observed significant effect of the inoculation with Azospirillum brasilense for plant height, ear height, and for genotype interaction vs. nitrogen supply with lower incidence for Fusarium spp, also observed grain yield increase. Were identified responsive genotypes to inoculation, even though they did not present higher values of grain yield compared to nitrogen fertilization, yield was maintained only with the use of Azospirillum brasilense, and the response was variable in each genotype. It is interesting the continuity of the research directing breeding programs with the aim of selecting genotypes responsive to inoculation.
Maize needs high amounts of nitrogen, for this it is interesting to search alternative methods that promote greater economic and environmental sustainability. As the use of inoculation with bacteria of the genus Azospirillum, able to perform the biological fixation of nitrogen and the production of growth hormones. The aim was to evaluate and characterize the agronomic performance of maize genotypes submitted different treatments for nitrogen supply (chemical and biological). The experiment was carried out in 2017 in first crop 2017/2018 and second crop 2017 in Jaboticabal-SP, using 48 maize genotypes in a randomized block design with two replicates as follows: 1) 140 kg.ha-¹ of nitrogen via urea in the cover, as chemical fertilization 2) Azospirillum brasilense inoculation at concentration of 600 mL.ha- ¹ via soil, as biological fertilization. The evaluated traits were: grain yield, male and female flowering, plant height, ear height, lodging, stalk breakage, stunt incidence, and Fusarium spp. Data were submitted to analysis of variance (Test F), the means by the Scott-Knott test and multivariate statistical analysis was performed by principal components. We observed significant effect of the inoculation with Azospirillum brasilense for plant height, ear height, and for genotype interaction vs. nitrogen supply with lower incidence for Fusarium spp, also observed grain yield increase. Were identified responsive genotypes to inoculation, even though they did not present higher values of grain yield compared to nitrogen fertilization, yield was maintained only with the use of Azospirillum brasilense, and the response was variable in each genotype. It is interesting the continuity of the research directing breeding programs with the aim of selecting genotypes responsive to inoculation.
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Palavras-chave
Zea mays L, Bactéria diazotrófica, Nitrogênio, Primeira e segunda safra, Produtividade de grãos