Estrutura da comunidade de Chironomidae (Diptera) em dois subsistemas em diferentes estados de conservação de uma planície de inundação do sul do Brasil Abstract: Aim: Our study aimed to compare the composition, distribution, diversity, abundance and dominance of Chironomidae in two subsystems of the Upper Paraná River floodplain, with different levels of conservation. We expected to find the highest values of diversity and lowest dominance of taxa in the most conserved areas (Ivinhema subsystem). We also expected to detect differences in the composition and distribution of communities between the subsystems, because of the level of conservation of each subsystem; Methods: Sampling was performed in March and September 2003, in eight stations, four in the Paraná River subsystem and four in the Ivinhema River subsystem. Four samples were taken at each point with a modified Petersen-type sampler: three for biological analysis and one for sedimentological analysis. Chironomidae larvae were identified to generic level; Results: Twenty-nine genera belonging to three subfamilies (Tanypodinae, Chironominae and Orthocladiinae) were recorded in this study. Chironomus, Dicrotendipes, Goeldichironomus, and Tanypus were the main genera found in the Paraná subsystem. Polypedilum was the only genus present in all sampling stations, and was dominant in five of them. In the Paraná subsystem we observed the highest values of dominance, and in the Ivinhema subsystem the largest number of rare taxa; Conclusions: Results showed differences in the structure of the Chironomidae community between the Paraná and Ivinhema subsystems. The community of Chironomidae in the Paraná subsystem was composed predominantly by generalist and tolerant genera. In the Ivinhema subsystem we observed higher richness of taxa. The greatest diversity, lowest values of dominance and exclusive taxonomic composition in the Ivinhema River subsystem could be reflecting a less degraded environment, demonstrating that the conservation of these areas is essential for maintaining the diversity of Chironomidae.Keywords: Chironomidae larvae, anthropic influences, diversity, Paraná River, Ivinhema River.Resumo: Objetivo: Esse estudo teve por objetivo comparar a composição taxonômica, distribuição, diversidade, abundância e dominância da comunidade de Chironomidae em dois subsistemas da Planície de inundação do alto rio Paraná em diferentes estados de conservação. Esperava-se encontrar maiores valores de diversidade e menor dominância de táxons nas áreas mais conservadas (subsistema Ivinhema). Esperava-se também, diferenças na composição e na distribuição da comunidade entre os subsistemas devido a aos diferentes estados de conservação de cada estação; Métodos: As coletas foram realizadas em março e setembro de 2003 em oito ambientes, quatro no subsistema Paraná e quatro no subsistema Ivinhema. Em cada ponto foram coletadas quatro unidades amostrais por período com um pegador do tipo Petersen modificado: três para análise biológica e uma para análise sedimentológica.

Environmental stress can directly or indirectly affect the formation of reactive oxygen species. Oxidative stress damages cell constituents such as carbohydrates, lipids, nucleic acids and proteins, reducing plant growth, respiration and photosynthesis. In recent decades, evidence has shown that small doses of selenium act as an antioxidant and plant biostimulant, promoting growth and improving resistance to abiotic stress such as drought. As such, the aim of this study was to assess the effect of selenium foliar feeding (0, 150 and 300 ppm) on the antioxidant activity, water use efficiency and yield traits of arugula grown with and without drought stress (50% and 100% ETc) in a protected environment. A randomized block design was used, with a 2x3 factorial scheme and four repetitions. Antioxidant activity increased in treatments with 150 ppm of fertilizer and exposure to drought stress. Plants in these treatments obtained higher water use efficiency, yield and leaf area values than those not submitted to drought stress.

Maintaining an adequate water supply is essential to obtain maximum yields in vegetable crops. As such, this study aimed to determine the water requirements (ETc) and crop coefficients (Kc) of arugula grown in a protected environment under subtropical climate conditions. The experiment was conducted in a greenhouse at the Center for Irrigation Technology of the State University of Maringá in Maringá, Paraná state (PR), Brazil. Crop evapotranspiration (ETc) was determined using three constant water table lysimeters and reference evapotranspiration with the Penman-Monteith equation. The total water consumption of the arugula crop was 113.27 mm. The average values obtained for the crop coefficients in the initial, mid-and late-season stages were 1.92, 1.03 and 1.80, respectively.