TOLERÂNCIA GENÉTICA DE LINHAGENS DE MILHO AOS HERBICIDAS TEMBOTRIONE E NICOSULFURON
DOI:
https://doi.org/10.18512/1980-6477/rbms.v17n2p317-327Keywords:
Zea mays L., retrocruzamento assistido por marcadores moleculares (RCAM), manejoAbstract
RESUMO - As plantas daninhas constituem um dos fatores que reduzem a produtividade do milho e, portanto, é importante conhecer o mecanismo de tolerância da cultura aos herbicidas, de forma a fornecer informações que minimizem os riscos de danos aos cultivos. Dessa forma, o objetivo do trabalho foi avaliar a resposta de linhagens de milho e o controle genético envolvido na tolerância aos herbicidas nicosulfuron e tembotrione. Duzentas e cinco linhagens de milho foram avaliadas quanto à reação aos herbicidas. Para a avaliação do controle genético de tolerância aos herbicidas foram empregadas duas linhagens tolerantes e duas sensíveis, as quais foram intercruzadas empregando um dialelo de meia tabela. As linhagens e as populações oriundas desses cruzamentos foram avaliadas quanto à reação aos herbicidas em delineamento de blocos casualizados com quatro repetições. As dosagens foram de 60 g ha-1 de nicosulfuron (Sanson®) e 100 g ha-1 de tembotrione (Soberan®). A avaliação fenotípica constituiu-se de número de plantas sensíveis e/ou tolerantes e o teste do Qui-quadrado (χ2) foi utilizado nas análises. Quanto à resposta à aplicação dos agroquímicos verificaram-se linhagens tolerantes ou sensíveis a ambos os herbicidas ou apenas a um deles. Nas avaliações do controle genético, as análises evidenciaram um gene com dominância completa que, pela análise de segregação das famílias F3, permitiu levantar a hipótese de genes fortemente ligados ou pleiotrópicos. Os resultados obtidos, associados ao retrocruzamento assistido por marcadores moleculares (RCAM), auxiliaram o processo de introgressão da tolerância nas linhagens sensíveis aos herbicidas nicosulfuron e tembotrione.
Palavras-chave: Zea mays L., herança, melhoramento genético, marcadores moleculares.
GENETIC TOLERANCE OF MAIZE LINES TO TEMBOTRIONE AND NICOSULFURON
ABSTRACT - As weeds are one of the factors that reduce maize productivity it is important to know the mechanism of crop tolerance to herbicide in order to minimize the risk of damage to the plants. Thus, the objective of this work was to evaluate the response of maize inbred lines and the genetic control of the tolerance to the herbicides nicosulfuron and tembotrione. Two hundred and five maize inbred lines were evaluated for herbicides reaction. For the evaluation of the genetic control of tolerance to herbicides, two tolerant and two sensitive inbred lines were used, which were intercrossed using a half diallel table. The inbred lines and the populations obtained from these crosses were evaluated for reaction to the herbicides in a randomized complete block design with 4 replicates. The dosages were 60 g ha-1 of nicosulfuron (Sanson™) and 100 g ha-1 of tembotrione (Soberan™). The phenotypic evaluation was based on the number of sensitive and / or tolerant plants and the chi-square test (χ2) was used in the analysis. Regarding the response to the application of the agrochemicals, inbred lines were tolerant or sensitive to one or both herbicides. The analysis of genetic control showed a gene with complete dominance, and the segregation analysis of the F3 families hypothesized the occurrence of strongly linked or pleiotropic genes. The data obtained associated to marker-assisted backcrossing allowed the tolerance introgression in sensitive inbred lines to nicosulfuron and tembotrione.
Keywords: Zea mays L., inheritance, plant breeding, molecular markers.
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