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penaherreracolina_la_dr_jabo.pdf: 769062 bytes, checksum: 47066271d117244ae5db733125346644 (MD5) === Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) === Iniap === A deriva de produtos fitossanitários e os efeitos sobre culturas-não-alvo são grandes preocupações na agricultura moderna, especialmente com produtos herbicidas que promovem efeitos com quantidades muito pequenas. Assim, o objetivo deste trabalho foi avaliar os efeitos de sub doses de glyphosate sobre seis híbridos de milho (Zea mays). Para tanto, foram conduzidos dois experimentos iniciais (Experimentos 01 e 02), com seis híbridos (Celeron, Fórmula, Impacto, Maximus, Speed e Status) e seis doses do herbicida glyphosate (formulação Roundup Ready®). No primeiro experimento foram avaliados os efeitos das doses 0, 25, 50, 75, 100 e 125 g e.a ha-1 e, no segundo experimento, as doses de 0, 100, 125, 150, 175 e 200 g e.a ha-1. Para avaliação de dose resposta um terceiro experimento (Experimento 03) foi conduzido com as doses de 0, 40, 80, 120, 160 e 200 g e.a ha-1 de glyphosate (Roundup Ready®) para os seis híbridos. Um quarto experimento (Experimento 04), também do tipo dose-resposta, envolvendo dois híbridos (Status e Impacto), as doses 0, 40, 80, 120, 160 e 200 g e.a ha-1 de glyphosate e as formulações Roundup Ready®, Roundup WG® e Zapp QI®. As plantas de milho foram cultivadas em vasos com mistura de terra, areia e esterco e a aplicação do glyphosate sempre ocorreu em plantas no estádio de quatro folhas totalmente expandidas. No experimento 01 foram avaliadas as variáveis fotossintéticas, morfológicas e nutricionais nos tratamentos com maior efeito tóxico. No experimento 02 incluiu-se altura das plantas na avaliação. Nos experimentos 03 e 04 foram avaliadas apenas variáveis morfológicas. A atividade fotossintética aos 7 DAA foi favorecida pela aplicação de glyphosate em doses de até 50 g e.a ha-1 apenas nos híbridos Impacto e Fórmula. O híbrido Celeron apresentou maior acúmulo... === Pesticides drift and its effect on non-target crops are the major concerns in modern agriculture, especially with the use of herbicides promoting effects at very small quantities. The objective of this study was to evaluate the effects of sub doses of glyphosate on six corn (Zea mays) hybrids, Two initial tests (01 and 02) were conducted with six maize hybrids (Celeron, Fórmula, Impact, Maximus, Speed, and Status) and six doses of the herbicide glyphosate (Roundup-Ready ®). In the first experiment the effects of 0, 25, 50, 75, 100 and 125 g e.a ha-1 and in the second experiment, doses of 0, 100, 125, 150, 175 and 200 g e.a ha-1 were evaluated. A third test (test 03) was carried out toy evaluate the dose-response at 0, 40, 80, 120, 160 and 200 g e.a ha-1 of glyphosate (Roundup®) on the six maize hybrids. A fourth trial (Trial 04), also a dose-response approach was conducted, involving two hybrids (Status and Impact), using 0, 40, 80, 120, 160 and 200 g e.a ha-1 of glyphosate and the commercial formulations Roundup Ready ®, Roundup WG® and Zapp QI®. Maize plants were grown in 4-L pots with a mix of soil, sand and manure. Glyphosate spraying always occurred at four fully expanded leaves maize stage. In test 01 it was evaluated photosynthetic, morphological and nutritional variables, mainly in the treatments with major toxic symptoms. In experiment 02 it was included plant height in the evaluations. In tests 3 and 4 only morphological variables were evaluated. The photosynthetic activity at 7 days after spraying was enhanced by application of glyphosate at doses up to 50 g e.a ha-1 only for the hybrids ‘Impact’ and ‘Fórmula’. The ‘Celeron’ showed greater leaf area and higher accumulation of dry mass of stem and leaf compared with the other genotypes and doses up to 50 g e.a ha-1 glyphosate favored this performance. Hybrids... (Complete abstract click electronic access below)
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