Ethoxysulfuron no controle de plantas daninhas na cultura do feijoeiro comum

It is necessary to identify new herbicides with a wide spectrum of weed control for bean crops, and have an adequate security margin for this crop. The main objectives of this work were to evaluate the potential use of ethoxysulfuron herbicide on controlling weeds and three soybean cultivars between bean crop, as the tolerance of IAC Imperador bean cultivar to this herbicide. An experiment was conducted on field with a split-plot design. At the whole plot were allocated the doses of ethoxysulfuron (0; 10.4; 20.8; 41.6; 62.5; and 83.3 g ha-1) and, at the subplots, the three soybean cultivars (AMS Tibagi, Dow 5D634 e Nidera 5909) were allocated with weeds (Bidens spp., Ipomoea spp.). Additionally, it was included an extra treatment without weeds and herbicide application. The Ethoxysulfuron controlled Ipomoea spp. and soybean plants, but didn’t control Bidens spp. It was found a differential tolerance between the soybean cultivars, and the AMS Tibagi cultivar showed to be slightly tolerant. Doses up to 20.8 g ha-1 are sufficient to satisfactorily control Ipomoea spp. and soybean plants, but not for Bidens spp. The herbicide provided an increment of bean yield, however, it wasn’t enough to achieve the extra treatment yield. The IAC Imperador bean cultivar showed moderate tolerance to ethoxysulfuron, and its plants can recover quickly after any injurie.É necessário identificar novos herbicidas com amplo espectro de controle de plantas infestantes para a cultura do feijão e, que possuam margem de segurança adequada para a cultura. Os objetivos deste trabalho foram, avaliar o potencial uso do herbicida ethoxysulfuron para o controle de plantas infestantes em meio a cultura do feijão, assim como a tolerância da cultivar de feijão IAC Imperador a este herbicida. Um experimento foi conduzido a campo em delineamento de blocos ao acaso com parcelas subdivididas. Nas parcelas principais foram alocadas as doses de ethoxysulfuron (0; 10,4; 20,8; 41,6; 62,5 e 83,3 g ha-1) e nas sub parcelas três cultivares de soja (AMS Tibagi, Dow 5D634 e Nidera 5909) + as plantas infestantes (Bidens spp., Ipomoea spp.). Adicionalmente foi incluído um tratamento extra sem infestantes e sem aplicação do herbicida. Ethoxysulfuron controlou as plantas de Ipomoea spp. e soja, mas não as de Bidens spp. Constatou-se tolerância diferencial entre as cultivares de soja avaliadas, em que a cultivar AMS Tibagi indica ser ligeiramente mais tolerante que as demais cultivares. Doses de até 20,8 g ha-1 são suficientes para controlar satisfatoriamente plantas de Ipomoea spp. e soja, no entanto, não as de Bidens spp. O herbicida proporcionou incremento no rendimento de grãos de feijão, todavia, não foi suficiente para alcançar o rendimento da testemunha extra. A cultivar de feijão IAC Imperador demostrou tolerância moderada ao ethoxysulfuron, além disso, as plantas tendem a se recuperar rapidamente da injúria do herbicida

Methods to promote Borreria latifolia seed germination

ABSTRACT Specific knowledge on dormancy and germination patterns of weed species aids the development of integrated management strategies. This study aimed to evaluate and select effective methods for overcoming dormancy in B. latifolia seeds, as well as determining their influence on the germination process. A completely randomized experimental design was used, with four replications and 20 seeds per repetition. Seven tests were conducted, with the corresponding B. latifolia seed treatments: Test 1 - mechanical scarification, sulfuric acid, hot water and running water; Test 2 - pre-cooling at 4 °C and dry heat at 60 °C. Test 3 - gibberellic acid at concentrations of 0, 50, 100, 200 and 400 ppm; Test 4 - acetic acid and potassium nitrate 2%; Test 5 - dual combinations of the three best treatments observed in the first four tests. Test 6 - pre-soaking in a sandbox and in germination paper and; Test 7 - imbibition curve. The seeds were submitted to the germination test in BOD at 25 °C with a photoperiod of 12h, in transparent polypropylene boxes. Germination percentage (GP), mean germination time and relative frequency of germination were determined and the weight of the seeds after soaking in Test 7 was measured. The best treatments for overcoming seed dormancy were dry heat, gibberellic acid 283 ppm and KNO3 3h. The association of dry heat + potassium nitrate 3 h and potassium nitrate 3 h +gibberellic acid increased germination percentage by 25% compared to isolated treatments

Superação de dormência em sementes de três espécies de Ipomoea

O conhecimento do método de superação de dormência mais adequado para cada espécie auxilia na identificação do tipo de dormência, bem como na definição de estratégias de manejo que permitam o controle mais eficaz. As espécies do gênero Ipomoea encontram-se amplamente distribuídas nos estados brasileiros, as mais comumente encontradas em lavouras de soja na região Sudoeste do Paraná são I. purpurea, I. indivisa e I. grandifolia. Assim, neste trabalho, o objetivo foi selecionar métodos eficazes de superação da dormência nas espécies Ipomoea indivisa, I. grandifolia e I. purpurea e determinar como eles influenciam na cinética da germinação das sementes dessas espécies. Os tratamentos utilizados foram água quente, escarificação mecânica, escarificação mecânica + resfriamento, escarificação química e testemunha. Na avaliação do efeito dos tratamentos, determinou-se a porcentagem de germinação, tempo médio, índice de velocidade e frequência relativa de germinação. A escarificação com ácido sulfúrico incrementou a germinação das sementes de I. indivisa e I. purpurea e o índice de velocidade de germinação àquelas de I. purpurea. O tratamento com água quente foi o mais eficiente em promover a germinação das sementes de I. grandifolia, e em reduzir o tempo médio de germinação das sementes de I. grandifolia e I. purpurea, de forma que, nos tratamentos de superação de dormência, há sincronização do processo de germinação

Methods to promote Borreria latifolia seed germination

<div><p>ABSTRACT Specific knowledge on dormancy and germination patterns of weed species aids the development of integrated management strategies. This study aimed to evaluate and select effective methods for overcoming dormancy in B. latifolia seeds, as well as determining their influence on the germination process. A completely randomized experimental design was used, with four replications and 20 seeds per repetition. Seven tests were conducted, with the corresponding B. latifolia seed treatments: Test 1 - mechanical scarification, sulfuric acid, hot water and running water; Test 2 - pre-cooling at 4 °C and dry heat at 60 °C. Test 3 - gibberellic acid at concentrations of 0, 50, 100, 200 and 400 ppm; Test 4 - acetic acid and potassium nitrate 2%; Test 5 - dual combinations of the three best treatments observed in the first four tests. Test 6 - pre-soaking in a sandbox and in germination paper and; Test 7 - imbibition curve. The seeds were submitted to the germination test in BOD at 25 °C with a photoperiod of 12h, in transparent polypropylene boxes. Germination percentage (GP), mean germination time and relative frequency of germination were determined and the weight of the seeds after soaking in Test 7 was measured. The best treatments for overcoming seed dormancy were dry heat, gibberellic acid 283 ppm and KNO3 3h. The association of dry heat + potassium nitrate 3 h and potassium nitrate 3 h +gibberellic acid increased germination percentage by 25% compared to isolated treatments.</p></div

Temporal selectivity of saflufenacil herbicide for the common bean crop of a brazilian oxisol

The temporal selectivity of an herbicide refers to the time interval required between its soil application and crop sowing to prevent damage to crop development and reproduction. Using field bioassays, this study aimed to determine the temporal sensitivity of the herbicide saflufenacil when used with a crop. The study was conducted in two time periods during 2011/2012 and 2012/2013 and employed a split-plot, randomized block experimental design. The main plots were assigned to seven time intervals between herbicide application and bean sowing (0, 5, 10, 15, 25, 35, and 50 days), and the subplots were assigned to groups in which saflufenacil was absent or present (0 and 29.4 g ai ha-1). We determined the stand and the plant height at 7, 14, and 21 days after sowing (DAS), and the first pod height, the number of pods per plant, the number of seeds per pod and the grain yield at maturity. Saflufenacil negatively affected the development of the IPR-Tiziu bean; at 21 DAS, the stand and the plant height at maturity were the variables most sensitive to the herbicide. A minimum interval of 15 days between herbicide spraying and bean sowing was necessary to prevent a reduction in grain yield.

Integração de coberturas mortas com atrazina para manejo de plantas daninhas na cultura do milho

The use of cover crops can contribute to the reduction of the dose required for weed control. The aim of this work was to assess the growth of weeds and productivity of corn from different degrees of black oat cover and velvet bean and atrazine doses. Two experiments were conducted in the experimental area, both was conducted in randomized blocks in a split plot design with four replications. In the main plots were randomized, four straw levels (0, 0.75, 1.5 and 3 times the amount originally produced) oat (Exp 1) or velvet bean (Exp 2). In the subplots were randomized to four doses of atrazine (0, 2100, 4200 and 8400 g ha-1). It was evaluated the weed density and crop yield. The utilization of straw species coverage on the ground, even at high levels, was not enough to exercise total control of weeds. Atrazine was not effective in weed control only in the treatment with 2100 g ha-1 of the herbicide and no velvet bean straw on the ground, but the straw of this species realized suppressive effect, supplementing the effect of the herbicidal dose. Levels in 2775 and 5550 kg ha-1 of velvet bean straw reduce the productivity of corn. Integrating the use of oat or velvet bean straw with low dose of atrazine (2100 g ai ha-1), results in effective weed control systems and more suitable cropping systems in the environmental aspect, both by reducing the use of herbicides as taking advantage of the benefits of no-till system.O uso de plantas de cobertura do solo pode contribuir para a redução da dose necessária para o controle de plantas daninhas. O objetivo deste trabalho foi avaliar o desenvolvimento de plantas daninhas e a produtividade da cultura do milho a partir de diferentes níveis de cobertura de aveia preta e mucuna preta e doses de atrazina. Dois experimentos foram realizados a campo, em delineamento de blocos ao acaso, em parcelas subdivididas, com quatro repetições. Em ambos experimentos, nas parcelas principais foram alocados quatro níveis de palha (0, 0,75, 1,5 e 3 vezes a quantidade originalmente produzida). O primeiro experimento foi constituído de palha de aveia preta e o segundo de palha de mucuna preta. Nas subparcelas de ambos experimentos foram alocadas quatro doses de atrazina (0, 2100, 4200 e 8400 g ha-1). Foram avaliadas a densidade de plantas daninhas e a produtividade da cultura. A utilização da palha das espécies de cobertura sobre o solo, mesmo em níveis elevados, não foi suficiente para exercer o controle pleno das plantas daninhas. A atrazina não foi eficiente no controle das plantas daninhas apenas no tratamento com 2100 g ha-1 do herbicida e ausência de palha de mucuna preta sobre o solo, mas a palha desta espécie de cobertura exerceu efeito supressor, complementando o efeito desta dose de herbicida. Os níveis de 2775 e 5550 kg ha-1 de palha de mucuna preta reduzem a produtividade do milho. A integração do uso de palha de aveia preta ou de mucuna preta com a utilização de dose baixa de atrazina (2100g ia ha-1), resulta em sistemas de cultivo eficazes no controle de plantas daninhas e mais adequados quanto ao aspecto ambiental, tanto pela redução do uso de herbicidas quanto pelo aproveitando dos benefícios do sistema de plantio direto