Períodos de dessecação de Urochloa ruziziensis e seu reflexo na produtividade da soja RR
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Data
2012-09-01
Autores
Nepomuceno, M. P.
Varela, R. M.
Alves, P. L. C .A. [UNESP]
Martins, J. V. F.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira da Ciência das Plantas Daninhas
Resumo
Com o objetivo de avaliar os efeitos de períodos de dessecação de Urochloa ruziziensis na implantação e na produtividade da soja transgênica no sistema de plantio direto, foram conduzidos dois experimentos em campo, nos municípios de Colina-SP, no ano agrícola de 2007/08, e Jaboticabal-SP, em 2009/10. em Colina, utilizou-se uma área de pastagem de U. ruziziensis, conduzida há sete anos. Nesse local foram testados quatro períodos de dessecação da cobertura vegetal: 30, 20, 10 e 0 dias antes da semeadura da soja. No experimento de Jaboticabal, a área utilizada tinha histórico de pastagem com U. ruziziensis, que no ano agrícola 2008/09 foi cultivada com milho. Após a colheita do milho ocorreu reinfestação natural de U. ruziziensis na área, correspondendo a mais de 80% de cobertura vegetal. Nesse experimento, os tratamentos corresponderam a seis períodos de dessecação: 25, 20, 16, 12, 7 e 0 dias após a aplicação. Nos dois experimentos utilizou-se 1,44 kg e.a. ha-1 do herbicida glyphosate e o cultivar de soja M-SOY 7908 RR. O delineamento experimental foi o de blocos ao acaso, com quatro repetições. Foram avaliados o estande da cultura aos 20 dias após a semeadura da soja e na pré-colheita, a altura de plantas, a altura de inserção da primeira vagem, o número de vagens por planta e o rendimento de grãos (produtividade estimada em kg ha-1). Os resultados foram submetidos à análise de variância (teste F), com as médias sendo comparadas pelo teste de Tukey a 5% de probabilidade. A dessecação de U. ruziziensis no mesmo dia da semeadura da soja reduziu a altura das plantas, o número de vagens por planta e a produtividade de grãos. O período recomendado para o manejo químico de U. ruziziensis com glyphosate está entre 10 e 20 dias antes da semeadura da soja. Pôde-se concluir que o período de dessecação de U. ruziziensis alterou a produtividade da cultura.
Two field trials were carried out to evaluate the effects of burn-down timing of Urochloa ruziziensis on transgenic soybean establishment and yield under the no-tillage system. One experiment was conducted in Colina, SP - Brazil, in 2007/2008 season, and the other in Jaboticabal, SP - Brazil, 2009/2010 season. In 2007/2008, the experiment was carried out in a 7-year-old grass pasture of U. ruziziensis, with four burn-down timings of vegetation cover being tested 30, 20, 10, and 0 days in advance to soybean sowing. In 2009/2010, the experiment was conducted in an old grass pasture of U. ruziziensis cropped with maize the summer before. After maize harvesting, a natural re-infestation of U. ruziziensis occurred, corresponding to more than 80% of the vegetation cover. In this experiment, treatments corresponded to six burn-down timings of vegetation cover 25, 20, 16, 7, and 0 days in advance to soybean sowing. In all experiments, 1.44 kg a.e. ha-1 of herbicide glyphosate was applied, and the soybean cultivar M-SOY 7908 RR was used. The experiments were arranged in a randomized block design, with four replicates. The evaluations were carried out by measuring crop stand 20 days after sowing and pre-harvest, plant height, first pod insertion height, number of pods per plant, grain yield, and estimated yield. Data were submitted to ANOVA and the Tukey test at 5% of probability. Burn-down of U. ruziziensis performed at the same day of crop sowing reduced plant height, number of pods per plant, and crop grain yield. Burn-down timing of U. ruziziensis using glyphosate was recommended to be between 10 and 20 days in advance to crop sowing. In conclusion, soybean yield was affected by burn-down timing of U. ruziziensis.
Two field trials were carried out to evaluate the effects of burn-down timing of Urochloa ruziziensis on transgenic soybean establishment and yield under the no-tillage system. One experiment was conducted in Colina, SP - Brazil, in 2007/2008 season, and the other in Jaboticabal, SP - Brazil, 2009/2010 season. In 2007/2008, the experiment was carried out in a 7-year-old grass pasture of U. ruziziensis, with four burn-down timings of vegetation cover being tested 30, 20, 10, and 0 days in advance to soybean sowing. In 2009/2010, the experiment was conducted in an old grass pasture of U. ruziziensis cropped with maize the summer before. After maize harvesting, a natural re-infestation of U. ruziziensis occurred, corresponding to more than 80% of the vegetation cover. In this experiment, treatments corresponded to six burn-down timings of vegetation cover 25, 20, 16, 7, and 0 days in advance to soybean sowing. In all experiments, 1.44 kg a.e. ha-1 of herbicide glyphosate was applied, and the soybean cultivar M-SOY 7908 RR was used. The experiments were arranged in a randomized block design, with four replicates. The evaluations were carried out by measuring crop stand 20 days after sowing and pre-harvest, plant height, first pod insertion height, number of pods per plant, grain yield, and estimated yield. Data were submitted to ANOVA and the Tukey test at 5% of probability. Burn-down of U. ruziziensis performed at the same day of crop sowing reduced plant height, number of pods per plant, and crop grain yield. Burn-down timing of U. ruziziensis using glyphosate was recommended to be between 10 and 20 days in advance to crop sowing. In conclusion, soybean yield was affected by burn-down timing of U. ruziziensis.
Descrição
Palavras-chave
Brachiaria ruziziensis, Glycine max, cobertura vegetal, alelopatia, glyphosate, Brachiaria ruziziensis, Glycine max, vegetation cover, allelopathy, glyphosate
Como citar
Planta Daninha. Sociedade Brasileira da Ciência das Plantas Daninhas , v. 30, n. 3, p. 557-565, 2012.