Interaction of imazapic in the integrated system using sugarcane mulch residue, herbicide and vinasse on purple nutsedge growth

O objetivo deste trabalho foi avaliar o efeito da interação palha de cana-de-açúcar, herbicida imazapic e diferentes meios de aplicação de vinhaça no crescimento inicial da tiririca. O experimento foi realizado em casa de vegetação e em vasos dispostos em blocos ao acaso com quatro repetições, sendo avaliados os tratamentos: controle; apenas palha; apenas vinhaça; apenas o herbicida imazapic; palha + vinhaça; palha + herbicida; herbicida + vinhaça aplicada antes do herbicida; herbicida + vinhaça aplicada depois do herbicida; herbicida + vinhaça aplicada junto com o herbicida em mistura; palha + herbicida + vinhaça aplicada antes do herbicida; palha + herbicida + vinhaça aplicada depois do herbicida; e palha + herbicida + vinhaça aplicada junto com o herbicida em mistura. O imazapic foi aplicado na dose de 122,5 g ha-1 e, no tratamento onde a vinhaça foi aplicada em mistura com o herbicida, este foi diluído com água até ¼ do volume necessário e completado com vinhaça. O imazapic foi eficiente no controle da tiririca quando comparado com a testemunha. A aplicação isolada da vinhaça ou a adição de apenas a palha ao solo estimularam o crescimento da tiririca embora tenha reduzido a viabilidade dos tubérculos. Nos tratamentos sem palha, não houve diferença no crescimento da tiririca, quando a aplicação de vinhaça foi realizada antes ou depois do imazapic, sendo observado controle da espécie. Entretanto, quando em mistura com a vinhaça, o produto não controlou a tiririca. A presença da palha no tratamento onde foi aplicada vinhaça antes do herbicida reduziu a ação do imazapic, em comparação com aquele sem palha. O número de brotações e a altura média de plantas de tiririca foram maiores nos tratamentos com palha quando foi aplicado imazapic depois ou mesmo junto com a vinhaça. Sob palha, a aplicação de vinhaça após o herbicida ou em mistura com imazapic aumentou apenas o número de brotações.The objective of this paper was to evaluate sugarcane mulch residue, imazapic and vinasse application interaction on the initial development of purple nutsedge (Cyperus rotundus L.). A greenhouse experiment was set up using pots filled with soil, arranged in a randomized complete blocks design, with four replications, with the following treatments: check; straw alone; vinasse alone; imazapic alone; straw + vinasse; straw + herbicide; herbicide + vinasse applied before the herbicide; herbicide + vinasse applied together; straw + herbicide + vinasse applied after the herbicide; straw + herbicide + vinasse applied after the herbicide; and straw + herbicide + vinasse applied together. Imazapic was applied at the rate of 122.5 g ha-1 and in the treatment in which vinasse was applied mixed with the herbicide, this compound was diluted in water until ¼ of the volume needed, the remaining volume being completed with vinasse. Imazapic was efficient for purple nutsedge control when compared to the check. Application of vinasse alone or straw alone stimulated the growth of this weed, though tuber viability was reduced. In the treatments without straw there was no difference in purple nutsedge development when vinasse was applied before or after imazapic, though control of this weed species was attained. However, when mixed with vinasse, the herbicide did not control the weed. The presence of straw in the treatment in which vinasse was applied before imazapic reduced the action of this weed killer when compared with the treatment without straw. The number of sprouts and height of the purple nutsedge plants were enhanced by the treatments with straw when imazapic was applied after or even mixed with vinasse. Only the number of sprouts increased when vinasse was applied after or mixed with the herbicide in soil covered with straw

Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius $A$. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio

Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory

Atmospheric parameters, such as pressure (P), temperature (T) and density, affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of pressure and density. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle Physic