ABSTRACT. The aim of this study was to evaluate the diversity of rhizobial isolates obtained from root nodules of pigeonpea plants grown at the eastern edge of the Brazilian Pantanal. The bacterial isolates were isolated from root nodules from field-growing pigeonpea grown in two rural settlements of the Aquidauana municipality. The bacterial isolates were characterized phenotypically by means of cultural characterization, intrinsic antibiotic resistance (IAR), salt and high incubation temperature tolerance, and amylolytic and cellulolytic activities. The molecular characterization of the bacterial isolates was carried out using amplified ribosomal DNA restriction analysis (ARDRA) and Box-polymerase chain reaction (PCR) techniques. In addition, the symbiotic performance of selected rhizobial isolates was evaluated in a greenhouse experiment using sterile substrate. The phenotypic characterization revealed that the bacterial strains obtained from pigeonpea root nodules presented characteristics that are uncommon among rhizobial isolates, indicating the presence of new species nodulating the pigeonpea plants in the Brazilian Pantanal. The molecular fingerprinting of these bacterial isolates also showed a highly diverse collection, with both techniques revealing less than 25% similarity among bacterial isolates. The evaluation of symbiotic performance also indicated the presence of microorganisms with high potential to increase the growth and nitrogen content at the shoots of pigeonpea plants. The results obtained in this study indicate the presence of a highly diversified rhizobial community nodulating the pigeonpea at the eastern edge of the Brazilian Pantanal.

The physical characteristics of a spray liquid are important in getting a good droplet formation and efficiency control over a target pest. These characteristics can be changed in various ways, the addition of mineral oil can be one of them. Thus, the aim of this study was to evaluate the physical characteristics of the surface tension of the diflubenzuron insecticide using different mineral oils in two concentrations and the interaction of droplets produced on the leaf surface of orange through the formed contact angle. Therefore, seven spraying liquids were prepared composed of diflubenzuron, often used in citrus for insect pest control, and three mineral oils (Argenfrut  , OPPA  and Nimbus  ) in two concentrations (0.25 e 0.5% v/v). Pendant droplets formed from these mixtures were measured to examine their impact on surface tension. Droplets were applied to the surface of orange leaves and the contact angle formed were measured. The addiction of the mineral oil to diflubenzuron reduce the surface tension and contact angles of droplets on leaf surfaces, resulting in a large surface area covered. Among the evaluated mineral oils, OPPA  and Nimbus  showed greater reduction in surface tension and smaller droplets contact angles on the orange leaf. Therefore, the application of the diflubenzuron with OPPA  or Nimbus  , at concentrations of 0.25 and 0.50%, provide a better spreadability of the sprayed droplets. Index terms: contact angle, surface tension, spreading.Características físicas de calda inseticida com óleo mineral e gotas formadas sobre folhas de citros RESUMO