Phytosociological studies are groups of methods that aim at the identification, composition and distribution of plant species in a community. The objective of this study was to identify and quantify the main weeds found in beans, maize and soybean cultivated in no-tillage and conventional systems. The experimental design was a randomized block one, with four replications. Experiments were conducted during three consecutive years, with summer crop (bean, maize and soybean) treatments, no-tillage system (NTS) composed by the covers, black oat, vetch and forage radish, in addition to their intercrop. In the conventional planting system (CTS), the area was left fallow in the off-season. The shoot dry matter of the covers was evaluated in each crop. The evaluated variables were: frequency, density, abundance, dry matter and the importance value index of the species in the area. Eighteen species of weeds and 12 families were identified, with Asteraceae and Poaceae families showing the highest number of individuals. The shoot dry matter production presented a difference among the covers; the cover black oat alone and intercrop with radish and vetch stood out, with the highest averages in the 3 years of the experiments. Cropping systems and different cover crops within the no-tillage system interfered in the number of encontered species. The emergence of Euphorbia heterophylla was favored, while the emergence of Lolium multiflorum was inhibited. E. heterophylla was the most encountered in the NTS areas, and its germination was negatively influenced by soil mobilization. The intercrop of black oat and vetch provided maximum weed control in soybean.

This study aimed to evaluate the waste cooking oil (WCO) hydrolysis in ultrasonic system using lipase as catalyst. Lipase was produced by the fungus Aspergillus niger via solid state fermentation (SSF) using canola meal as substrate. Prior to the hydrolysis reaction, the lipase behavior when subjected to ultrasound was evaluated by varying the temperature of the ultrasonic bath, the exposure time and the equipment power. Having optimized the treatment on ultrasound, the WCO hydrolysis reaction was carried out by evaluating the oil:water ratio and the lipase concentration. For a greater homogenization of the reaction medium, a mechanical stirrer at 170rpm was used. All steps were analyzed by experimental design technique. The lipase treatment in ultrasound generated an increase of about 320% in its hydrolytic activity using 50% of ultrasonic power for 25min. at 45°C. The results of the experimental design conducted for ultrasound-assisted hydrolysis showed that the best condition was using an oil:water ratio of 1:3 (v:v) and enzyme concentration of 15% (v/v), generating 62.67μmol/mL of free fatty acids (FFA) in 12h of reaction. Thus, the use of Aspergillus niger lipase as a catalyst for hydrolysis reaction of WCO can be considered as a possible pretreatment technique of the oil in order to accelerate its degradation.

Agricultural protection agents used in soil and crops, when applied conventionally, may have their activity impaired against pests and vectors due to their volatilization, photodegradation, leaching, and other unwanted occurrences caused by weather conditions. These problems cause economic and environmental damage due to the high volume of applications necessary for the farmer to achieve the desired results. The indiscriminate use of free pesticides causes high environmental pollution because these compounds are cumulative in soil, water and vegetation, sometimes causing air contamination, which can cause health issues in local workers and the death of animals. In contrast, nanopesticides are an alternative emerging technology that allows the controlled release of active compounds, improving pest control performance and turning it more sustainable and in line with the concept of precision agriculture. The use of nano-delivery systems for pesticide agents uses nanostructures capable of altering the release kinetics of these compounds, providing the plantation with an adequate amount for pest elimination. This paper presents an overview of nanopesticides, addresses some current concepts of sustainability, reviews and analyzes the latest developments regarding these nanomaterials, and provides an update on their advantages and disadvantages.

Na atualidade busca-se reduzir o uso de agrotóxicos, pois além dos prejuízos ambientais provocados por eles, existe a preocupação com o consumo de alimentos contaminados com possíveis resíduos. A presente revisão de literatura tem como objetivo abordar o uso de bioherbicidas, além de se avaliar as perspectivas e as potencialidades desses como formas de manejo de plantas daninhas infestantes de ambiente agrícola e não agrícola. Há a necessidade crescente de se descobrir novas moléculas ou métodos capazes de se controlar as plantas daninhas infestantes de áreas agrícolas e não agrícolas. Assim sendo os bioherbicidas vem despertando o interesse de pesquisadores, técnicos e produtores. Estes podem ser formulados a partir de substâncias produzidas pelo metabolismo secundário de vegetais e/ou de microrganismos. As pesquisas realizadas apontam o controle eficiente com o uso de bioherbicidas, principalmente relacionados aos processos de germinação e desenvolvimento das plantas daninhas, podendo em alguns casos apresentar potencial fitotóxico mesmo quando essas estiverem em estádios avançados. Os bioherbicidas, além de serem eficientes no controle das plantas daninhas, reduzem os prejuízos ambientais provocados pelo uso contínuo de herbicidas sintéticos. O Brasil apresenta potencial para se usar os bioherbicidas, tendo em vista a diversidade vegetal e os diversos sistemas de cultivos agrícolas praticados no país.

Brazil is the largest consumer of pesticides in the world. However, knowledge on how these pesticides affect wildlife is scarce. Among the vertebrates, amphibians are particularly important in research to assess the impact of pesticides because of the correlation between pesticide and the decline of these species. This study aimed to evaluate the acute and chronic toxicity of commercial formulations of pesticides, i.e., atrazine (herbicide), cypermethrin (insecticide), and tebuconazole (fungicide) in Physalaemus cuvieri tadpoles. Eggs were collected in nature and cultivated under controlled conditions in the laboratory. Toxicity tests were carried out under standard conditions to determine the lethal concentration (LC) after 96 h of exposure and to determine the effect of sublethal concentrations after 7 days. In addition, we performed swimming activity tests on tadpoles exposed to sublethal concentrations. The lethal concentration (LC) was 19.69 mg/L for atrazine, 0.24 mg/L for cypermethrin and 0.98 mg/L for tebuconazole. In the acute test, atrazine showed lower toxicity than cypermethrin and tebuconazole for P. cuvieri. Swimming activity was affected at sublethal doses of atrazine and cypermethrin, but was not after exposure to tebuconazole. Cypermethrin was the insecticide that most altered the swimming activity of the individuals tested. The risk evaluation analysis indicated risks for tadpoles exposed to three tested pesticides, specially cypermethrin.