Toxicity of herbicides used in the sugarcane crop to diazotrophic bacterium Herbaspirillum seropedicae [Toxicidade de herbicidas utilizados na cultura da cana-de-açúcar à bactéria diazotrófica Herbaspirillum seropedicae]
De Oliveira Procopio S.,Pesquisadores da Embrapa Tabuleiros Costeiros |
Fernandes M.F.,Pesquisadores da Embrapa Tabuleiros Costeiros |
Teles D.A.,Federal University of Sergipe |
Filho J.G.S.,Analista da Embrapa Tabuleiros Costeiros |
And 3 more authors.
Semina:Ciencias Agrarias | Year: 2014
The objective of this work was to identify herbicides used in the sugarcane crop that affects neither the growth, the development, of nor the process of biological nitrogen fixation (BNF) by the diazotrophic bacterium Herbaspirillum seropedicae. Eighteen herbicides (paraquat, ametryne, tebuthiuron, amicarbazone, diuron, metribuzin, [hexazinone + diuron], [hexazinone + clomazone], clomazone, isoxaflutole, sulfentrazone, oxyfluorfen, imazapic, imazapyr, [trifloxysulfuron sodium + ametryne], glyphosate, MSMA e 2,4-D) were tested in their respective commercial doses regarding their impact on the growth of the bacteria in liquid medium DIGs. For this, we determined the duration of lag phase, generation time and maximum cell density of H. seropedicae, calculated from optical density data obtained at regular intervals during the incubation of cultures for 33 h at 32oC. We also evaluated the impact of herbicides on nitrogenase activity of H. seropedicae grown in semi-solid N-free JNFb medium. The effects of herbicides on the growth variables and the ARA were compared with the untreated control by Dunnett test. A completely randomized design was used. The herbicides paraquat, imazapyr, ametryne, glyphosate and oxyfluorfen inhibited the growth of H. seropedicae in vitro. Ametryne, oxyfluorfen and glyphosate caused a small reduction in the duration of the lag phase of diazotrophic bacteria H. seropedicae. Oxyfluorfen, ametryne and imazapyr resulted in increased the generation time by H. seropedicae. Glyphosate promoted drastic reduction in biological nitrogen fixation in vitro by H. seropedicae. The other tested herbicides did not affect the growth or the same BNF by H. seropedicae.
Nava G.A.,Federal Technological University of Parana |
Marodin G.A.B.,Federal University of Rio Grande do Sul |
Santos R.P.D.,Federal University of Rio Grande do Sul |
Paniz R.,Federal University of Rio Grande do Sul |
And 2 more authors.
Revista Brasileira de Fruticultura | Year: 2011
The peach cultivar Granada is showing low fruit set and irregularity of yield in major producing regions of peach fruit in the state of Rio Grande do Sul, Brazil. This work aimed to compare the floral development and yield of 'Granada' peach tree in two regions with different climatic conditions. The orchards studied, in 2004 and 2005, are located in Charqueadas, in the Central Depression, and Canguçu, in the Southern State. The low yield and viability of pollen, associated to delay in the ovules development, mainly influenced by the high temperatures during the pre-flowering and flowering, were the causes of low reproductive and productive performance of 'Granada' peach tree at Charqueadas in 2004 and at Canguçu in 2005.
Paula J.M.,Federal University of Pelotas |
Vargas L.,Pesquisador da Embrapa Trigo |
Agostinetto D.,Federal University of Pelotas |
Nohatto M.A.,Federal University of Pelotas
Planta Daninha | Year: 2011
Horseweed (Conyza bonariensis), which belongs to the Asteraceae family, is a weed species widely spread in Brazil. Horseweed biotypes resistant to glyphosate, the main herbicide used in Roundup Ready soybean fields, were identified in the states of Rio Grande do Sul and Parana. The aim of this study was to evaluate the effect of different winter and pre-sowing management techniques on soybean plant population of C. bonariensis resistant to glyphosate. The results showed that the population of C. bonariensis is larger in areas maintained fallow than in areas planted with wheat or oats during the winter. Wheat and oats were found to exert a suppressive effect on the population of C. bonariensis, providing greater ease of control with herbicide before seeding in the culture used in succession. The control of glyphosate-resistant C. bonariensis was satisfactory when post-emergence herbicides were used in wheat crop and glyphosate and 2,4-D or glyphosate paraquat diuron in pre-planting soybeans.
Penetration resistance and soybean yield after mechanical intervention on an Oxisol under tillage [Resistência à penetração e rendimento da soja após intervenção mecânica em latossolo vermelho sob plantio direto]
Drescher M.S.,Federal University of Santa Maria |
Eltz F.L.F.,Federal University of Santa Maria |
Denardin J.E.,Pesquisador da Embrapa Trigo |
Faganello A.,Pesquisador da Embrapa Trigo |
Drescher G.L.,Federal University of Santa Maria
Revista Brasileira de Ciencia do Solo | Year: 2012
Compaction negatively affects a number of soil properties, e.g., resistance to root penetration and water and nutrient availability to plants, restricting the photosynthetic rate, shoot growth and consequently, the yield. When soil compaction becomes limiting to crop development, mitigation measures must be adopted. The purpose of this study was to evaluate the residual effect of mechanical soil plowing and chiseling, by a seeder with soil breakers (disks and disks plus short ripper) as mitigation practice of the soil compaction under no-tillage (NT), on soil penetration resistance and soybean yield. In 2001, a study was conducted in Coxilha, in northern Rio Grande do Sul, on an Oxisol, in an area with a sequence of NT management. In this field, every year a treatment of mechanical soil decompression was applied, consisting of plowing and chiseling the soil under NT, before sowing the summer crop, reassuming the NT management after this intervention. The experimental design consisted of randomized blocks in a split-plot design with three replications. The treatments consisted of a combination of 13 systems of soil management in the main plots and two seed drill devices in the subplots. Thus, the management systems were evaluated by the control, represented by the uninterrupted maintenance of NT for 16 years, six NT management periods (7.5, 6.5, 5.5, 4.5, 3.5, and 2.5 years) after one intervention with mechanical disc plow + disc harrow (A) and the same six NT management periods after one mechanical intervention with chiseling (E). The levels in the subplots consisted of the action of a no-till seeder equipped with double discs reaching a depth of 7 cm and a seeder equipped with double disks + short ripper reaching a depth of 13 cm. Results indicated that the mitigating effect on compaction and on the improvement of soil structure of the mechanical intervention in soil under consolidated NT consisting of soil chiseling or plowing is short-lived, with a residual effect of up to two and a half years for penetration resistance. The use of a no-till seeder drill equipped with short ripper + disc seeder has potential for mitigation of soil compaction, by reducing mechanical penetration resistance in the 7-15 cm layer. Nevertheless, the residual effect of mechanical intervention for soil decompaction and the adoption of different devices for fertilizer application in the plant furrow were not effective in altering the soybean yield in the 2008/2009 growing season.