Seletividade do nicosulfuron em três estádios fenológicos de milho-pipoca

Abstract

Seletividade do nicosulfuron em três estádios fenológicos ... 1Recebido para publicação em 15.6.2011 e aprovado em 16.12.2011. ) e três estádios fenológicos (V3, V5 e V7), totalizando 15 tratamentos. A resposta do milho-pipoca ao nicosulfuron foi verificada por meio de avaliações visuais de intoxicação e efeitos sobre a altura das plantas aos 7, 14 e 28 dias após a aplicação, componentes de produção (plantas m -2 , espigas m -2, comprimento de espigas, massa de 100 grãos e número de grãos por espiga) e produtividade de grãos. De modo geral, o híbrido A 448 White evidenciou maior nível de tolerância aos tratamentos aplicados no estádio V3. A produtividade de grãos não sofreu interferência significativa do nicosulfuron nos estádios V3 e V5, mesmo na dosagem mais alta. Assim, dentro do intervalo de dosagens avaliado, o herbicida nicosulfuron pode ser aplicado em plantas de milho-pipoca nos estádios V3 e V5, sem riscos de redução de produtividade.Palavras-chave: Zea mays, herbicida, sulfonilureias, tolerância.ABSTRACT -This work aimed to evaluate the selectivity of the herbicide nicosulfuron toward popcorn (hybrid A 448 White), applied at three growth stages. The experiment was arranged in a randomized complete block design, with four replications. The treatments were organized as a factorial combination, including five nicosulfuron doses (0; 17.5, 35, 70, and 140 g ha -1 ), and three growth stages (V3, V5, and V7), totaling fifteen treatments. The response of the hybrid to nicosulfuron was evaluated in terms of visual injury ratings and effects on plant height at 7, 14, and 28 days after application, yield components (plants m -2 , cob m -2 , cob length, 100 grains weight and kernels/cob), and final yield. In general, hybrid A 448 White showed a higher level of tolerance to the treatments applied at the V3 stage. Grain yield did not suffer significant interference of nicosulfuron at the V3 and V5 growth stages, even at the highest dose. Thus, at the dose range evaluated, nicosulfuron can be used safely at the V3 and V5 growth stages, without risk of reduced yield.

Chemical Weed Management in Grain Sorghum and Selectivity of Atrazine + S-Metolachlor to Different Hybrids

“…In addition to these herbicides, mesotrione (50 g ha -1 ) was also an interesting The results obtained in the study with different grain sorghum hybrids showed that there is a special tolerance to atrazine + s-metolachlor, and that selectivity is associated with the herbicide rate (Table 5). These differences were also found in a preliminary study with grain sorghum (Takano et al, 2016) and have been widely known and studied for different maize hybrid (Cavalieri et al, 2008(Cavalieri et al, , 2012. Therefore, the choice of the herbicide and rate to be applied, the hybrid variety to be planted and the crop management system should be taken into account in the strategy of weed control.…”

“…In corn, tolerance of commercial hybrids to sulfonylurea herbicides varies considerably, being high for some hybrids and low for others (Cavalieri et al, 2008). In addition, tolerance of maize hybrids may vary according to the environment, crop management system, herbicide rate and the plant stage during the herbicide application (Cavalieri et al, 2012;Guerra et al, 2010). In a study comparing five grain sorghum hybrids, the hybrid 50A50 was the least sensitive and recovered more rapidly on the evaluation of 18 herbicide treatments (Takano et al, 2016).…”