Toxicidade do herbicida S-metolachlor em plantas de milho provenientes de sementes com diferentes formatos e dimensões
Carregando...
Data
2006-06-01
Autores
Rosenthal, M. D. A.
Procópio, S. O.
Pinto, J. J. O.
Jacob Júnior, E. A.
Peres, W. B.
Manica, R.
Zanatta, J. F.
Cargnelutti Filho, A. [UNESP]
Sganzerla, D. C.
Carneiro, J. C.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira da Ciência das Plantas Daninhas
Resumo
Este trabalho teve como objetivo avaliar a toxicidade do herbicida S-metolachlor em plantas de milho oriundas de sementes com diferentes características morfológicas. O experimento foi conduzido em casa de vegetação, localizada no município de Capão do Leão, RS. Os tratamentos foram compostos pelas combinações de três grupos de tamanhos de sementes, classificadas em peneiras de crivo oblongo [sementes retidas nas peneiras de largura 14/64 (peneira 14), 18/64 (peneira 18) e 21/64 (peneira 21)], de dois formatos de sementes (chata e redonda) e de cinco doses do herbicida S-metolachlor (0,00; 0,48; 0,96; 1,44; e 1,92 kg ha-1), totalizando-se 30 tratamentos. O delineamento experimental utilizado foi o de blocos casualizados em esquema fatorial (3 x 2 x 5), com quatro repetições. Após a separação e classificação das sementes, procedeu-se à semeadura em vasos preenchidos com solo homogeneizado. em cada vaso foram semeadas oito sementes de milho, na profundidade de 3,0 cm, realizando-se, 24 horas depois, a aplicação do S-metolachlor em pré-emergência. Foram realizadas as seguintes avaliações: velocidade de emergência das plântulas; número total de plântulas emergidas; toxicidade visual e altura de plantas aos 7, 14 e 21 dias após a emergência (DAE); e biomassa seca das raízes e da parte aérea aos 21 DAE. O formato das sementes se mostrou fator importante na tolerância das plantas aos efeitos tóxicos do herbicida S-metolachlor, aplicado em pré-emergência, quando as sementes de milho são de menor tamanho, sendo observada maior toxicidade quando as plantas eram provenientes de sementes redondas. O aumento das doses aplicadas do S-metolachlor ocasionou reduções na aquisição de biomassa seca tanto da parte aérea como das raízes de plantas de milho, porém maior decréscimo se observou quanto ao acúmulo de biomassa seca das raízes.
This experiment aimed to evaluate the toxicity of the herbicide S-metolachlor in corn plants originated from seeds with different morphological characteristics. It was conducted under greenhouse conditions, in the municipal district of Capão do Leão, RS. The treatments consisted of combinations of three groups of seed size classified in an oblong sieve [seeds retained in sieve width of 14/64(sieve 14), 18/64sieve (sieve 18) and 21/64 sieve (sieve 21), in two seed formats (crushed and round) and five doses of the herbicide S-metolachlor (0.00; 0.48; 0.96; 1.44; and 1.92 kg ha-1), in 30 treatments. The experiment was arranged in a randomized block design in a factorial scheme (3 x 2 x 5), with four repetitions. After being separated and classified, the seeds were sown in vases filled with homogenized soil. In each vase eight corn seeds were sown at a depth of 3.0 cm, 24 hours after the application of Smetolachlor in pre-emergence. The following evaluations were performed: seedling emergence speed, total number of emerged seedlings; visual injury and height of seedlings at 7, 14 and 21 days after emergence (DAE); dry biomass of the roots and aerial part at 21 DAE. Seed format was found to be an important factor in plant tolerance to the toxic effects of Smetolachlor, applied in pre-emergence, for smaller corn seeds and greater toxicity when the plants were originated from round seeds. Increased S-metolachlor doses caused reductions in dry biomass acquisition, both in the aerial part and in the roots of the corn plants. However, a greater reduction was observed in dry biomass accumulation of the roots.
This experiment aimed to evaluate the toxicity of the herbicide S-metolachlor in corn plants originated from seeds with different morphological characteristics. It was conducted under greenhouse conditions, in the municipal district of Capão do Leão, RS. The treatments consisted of combinations of three groups of seed size classified in an oblong sieve [seeds retained in sieve width of 14/64(sieve 14), 18/64sieve (sieve 18) and 21/64 sieve (sieve 21), in two seed formats (crushed and round) and five doses of the herbicide S-metolachlor (0.00; 0.48; 0.96; 1.44; and 1.92 kg ha-1), in 30 treatments. The experiment was arranged in a randomized block design in a factorial scheme (3 x 2 x 5), with four repetitions. After being separated and classified, the seeds were sown in vases filled with homogenized soil. In each vase eight corn seeds were sown at a depth of 3.0 cm, 24 hours after the application of Smetolachlor in pre-emergence. The following evaluations were performed: seedling emergence speed, total number of emerged seedlings; visual injury and height of seedlings at 7, 14 and 21 days after emergence (DAE); dry biomass of the roots and aerial part at 21 DAE. Seed format was found to be an important factor in plant tolerance to the toxic effects of Smetolachlor, applied in pre-emergence, for smaller corn seeds and greater toxicity when the plants were originated from round seeds. Increased S-metolachlor doses caused reductions in dry biomass acquisition, both in the aerial part and in the roots of the corn plants. However, a greater reduction was observed in dry biomass accumulation of the roots.
Descrição
Palavras-chave
Zea mays, pré-emergência, acetamidas, Zea mays, Pre-emergence, acetamides
Como citar
Planta Daninha. Sociedade Brasileira da Ciência das Plantas Daninhas , v. 24, n. 2, p. 319-327, 2006.