Qualidade Biológica do Solo de Sistemas de Cultivo em Pomares de Citrus Deliciosa

The citrus production is grown in Rio Grande do Sul under different croppingsystems, and their impact on soil quality is unknown. The aim of thisstudy was to evaluate some measures of environmental quality between differentmanagement systems of Citrus from Vale do Caí, RS with emphasison the production of tangerines ‘Montenegrina’ (Citrus deliciosa Tenore) bychemical and biological characterization of soils. The samples were collectedfrom five areas cultivated under different cropping types: organic cropping(PO), organic cropping in transition to biodynamic (POT), agroforestry cropping(PAF), conventional cropping (PC) and native forestry (MN) as a controltreatment in the Montenegro city, Rio Grande do Sul, at 0-10 cm of depth. Wedetermined the microbial biomass carbon (CBM), basal respiration (RB), theactivities of urease, acid phosphatase (FA) and the hydrolysis of fluoresceindiacetate (FDA). For all evaluations, the results were significantly higher inthe control area (MN). In CBM evaluations, the control obtained values of175.2 mg C Kg-1 of dry soil and the lowest value was found in CP at 34 mg CKg-1 of dry soil. The values of RB to system PAF (334.4 mg C-CO2 kg-1 of dry soil), PO (333.3 mg C-CO2 kg-1 of dry soil) and LPO (257.7 mg C-CO2 kg-1 soildried) were significantly lower against the control (728.7 mg C-CO2 kg-1 drysoil). In the urease evaluation, the systems POT and PO were significantlylower with values of 77.7 and 68.5 µg N-NH4 g-1 of dry soil 2 h-1 respectively,compared with the control (128 µg N-NH4 g-1 of dry soil 2 h-1). For cropping systems of PC and PAF, FA values obtained were almost three folds lower(541 and 427 µg p-nitrofenol g-1 dry soil h-1 respectively) when compared withthe control area. So the cropping systems, even the less intensive, were notable to maintain the same quality of soil microbiology that areas of the nativeforestry. This shows that soil quality indicators such as RB, the FA and ureasecan be important indicators in assessing the environmental quality of differentcropping systems of Citrus deliciosa.A citricultura no RS é cultivada sob diversos sistemas de cultivos, sendo que o impacto destes na qualidade do solo é desconhecido. O objetivo deste estudo foi avaliar alguns índices de qualidade ambiental entre os diversos sistemas de manejo de citrus do Vale do Caí- RS com ênfase na produção de tangerinas ‘Montenegrina’ (Citrus deliciosa Tenore), através da caracterização química e biológica dos solos. As amostras foram coletadas em cinco áreas cultivadas sob diferentes sistemas de cultivo: sistema de cultivo orgânico (PO), cultivo orgânico em transição para biodinâmico (POT), cultivo agroflorestal (PAF), cultivo convencional (PC) e mata nativa (MN), no município de Montenegro, Rio Grande do Sul, a uma profundidade de 0-10 cm. Foram determinadas o Carbono da Biomassa Microbiana (CBM), a respiração basal (RB), as atividades da urease, da fosfatase ácida (FA) e a hidrólise do diacetato de fluoresceína (FDA). Para todas as avaliações, os resultados foram significativamente superiores na área de MN. Para o CBM, o sistema de MN obteve valores de 175,2 mg C Kg-1 de solo seco e o menor valor foi encontrado no sistema PC com 34 mg C Kg-1 de solo seco. Os valores de RB para o cultivo PAF (334,4 mg C-CO2 kg-1 solo seco), PO (333,3 mg C-CO2 kg-1 solo seco) e POT (257,7 mg C-CO2 kg-1 solo seco), foram significativamente menores nos valores de RB do sistema MN. Na avaliação da urease, os sistemas POT e PO foram significativamente inferiores apresentando valores de 77,7 e 68,5 µg N-NH4 g-1 solo seco 2 h-1 respectivamente, quando comparados ao sistema MN com valores de 128 µg N-NH4 g-1 solo seco 2 h-1. Para os sistemas de cultivo PC e PAF, os valores de FA obtidos foram quase três vezes menores (541 e 427 µg p-nitrofenol g-1 solo seco h-1 respectivamente) quando comparados com o sistema de MN. Portanto os sistemas de cultivo, mesmo os menos intensivos, não se mostraram capazes de manter a mesma qualidade microbiológica do solo que as áreas de MN da região. Isto mostra que indicadores de qualidade do solo como a RB, a FA e a urease podem ser indicadores importantes na avaliação da qualidade ambiental de diferentes sistemas de cultivo

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements