Tolerância de tubérculos de Cyperus rotundus, L. sob prolongada submersão em água.

A planta invasora, Cyperus rotundus, L. de habito perene, oferece considerável resistencia para todos os métodos de controle, sejam mecânicos, manuais, ou mesmo químicos, esses, possibilitando restrição ao seu crescimento e aumento de sua população. O controle biológico também não tem tido sucesso. Procura-se no presente relato, demonstrar sua tolerância a submersão, mesmo por períodos necessários para inundação do arroz, quando plantado em várzeas inundáveis. Essa plantação, tem a base das plantas submersas, ate a proximidade da colheita. Em media, isso perdura por 60 dias. Em ensaios conduzidos para testar a tolerância dos tubérculos de C. rotundus, em água e em água barrenta, confirmou-se que, a submersão por período de 119 dias, em qualquer dos meios citados, ainda deixa aproximadamente 10% de tubérculos viáveis, os quais, drenada a área ocupada pelo arroz, tem condições para rebrota e alastramento, sob as condições variáveis. Em um segundo ensaio, mantidos os tubérculos por período de 220 dias submersos, ainda foram viáveis 6% dos tubérculos que foram avaliados. Donde a conclusão, de que, somente por submersão não torna sucesso, o controle da planta invasora de habito perene que e o Cyperus rotundus, L. todavia, a redução obtida na população, já pode ser de utilidade, para a multiplicação, respeitadas com a complementação de outros métodos integrados no processo

Effects of glyphosate-resistant crop cultivation on soil and water quality

Transgenic glyphosate-resistant crops (GRCs) have been com- mercialized and grown extensively in the western Hemisphere and, to a lesser extent, elsewhere. GRCs have generally become dominant in those countries where they have been approved for growing. Potential effects of glyphosate on soil and water are minimal, compared to the effects of the herbicides that are re- placed when GRCs are adopted. Perhaps the most important indirect effect is that GRCs crops promote the adoption of re- duced- or no-tillage agriculture, resulting in a signifcant reduc- tion in soil erosion and water contamination. Glyphosate and its degradation product, aminomethylphosphonate (AMPA), residues are not usually detected in high levels in ground or surface water in areas where glyphosate is used extensively. Furthermore, both glyphosate and AMPA are considered to be much more toxico- logically and environmentally benign than most of the herbicides replaced by glyphosate

Potential environmental impacts of herbicide-resistant crops.

Transgenic bromoxynil-, glufosinate-, and glyphosate-resistant crops have been commercialized and grown extensively in the Western Hemisphere and, to a lesser extent, elsewhere. Bromoxynil-resistant crops have been removed from the market. Few new herbicide-resistant crops (HRCs) are likely to be introduced in the near future. Glyphosate-resistant cotton and soybean have become dominant in those countries where they can be grown. Previous and potential effects of glufosinate and glyphosate on contamination of soil, water, and air are minimal, compared to that caused by the herbicides that they replace when HRCs are adopted. No risks have been found with food or feed safety or nutritional value in products from currently available HRCs. Both glufosinate- and glyphosate-resistant crops promote the adoption of reduced- or no-tillage agriculture. In the U.S.A. and Argentina, the advent of glyphosate-resistant soybeans resulted in a significant shift to reduced- and no-tillage practices, strongly reducing environmental degradation by agriculture. Weed species in HRC fields have shifted to those that can more successfully withstand glyphosate or to those that avoid the time of its application. One weed species has evolved resistance in glyphosate-resistant crops. HRCs have greater potential to become problems as volunteer crops than do conventional crops. In canola, herbicide resistance transgenes have been found in fields of canola that are supposed to be non transgenic. Under some circumstances, tansgene flow (introgression) to plants that might become problems in natural ecosystems may be the largest risk of HRCs. The HRC transgene itself is highly unlikely to be a risk in wild populations, but when linked to transgenes that may impart fitness benefits outside of agriculture, natural ecosystems could be affected. The development and use of failsafe introgression barriers in crops with such linked genes is highly encouraged

Controle integrado de plantas daninhas em soja.

Danos causados pelas plantas daninhas; Principais especies ocorrentes no Parana e no Brasil; Situacao do uso de herbicidas; Meios de controle de plantas daninhas; Como escolher o herbicida; Caracteristicas e usos dos herbicidas; Consideracoes economicas sobre o controle de plantas daninhas; Consideracoes tecnicas sobre algumas alternativas de controle.bitstream/item/50750/1/4.pd