Utilisation d'une souche indigène de Trichoderma harzianum contre cinq agents pathogènes chez le concombre et la tomate de serre au Québec

Le potentiel antagoniste du biofongicide à base de Trichoderma harzianum MAUL-20, isolé au Québec, a été testé contre cinq agents telluriques phytopathogènes(Fusarium oxysporum f. sp. radicis-lycopersici (FORL), Pythium ultimum, Rhizoctonia solani, Sclerotinia sclerotiorum et Verticillium dahliae) du concombre et de la tomate de serre. Le biofongicide a démontré une efficacité contre P. ultimum et R. solani chez le concombre et la tomate et contre FORL chez la tomate. De plus, T. harzianum MAUL-20 a eu un effet stimulant sur le développement des plants de concombre lorsque cultivés, sans agents pathogènes, dans un substrat organique alimenté du biofongicide. L'efficacité de T. harzianum MAUL-20 a été comparée à celle du biofongicide américain Rootshield™ (Trichoderma harzianum KRL-AG2) et le premier a démontré une activité antagoniste égale ou supérieure à celle de Rootshield™.Trichoderma harzianum MAUL-20, a strain isolated from a soil in the province of Québec, was evaluated for its antagonistic potential against five plant pathogens (Fusarium oxysporum f. sp. radicis-lycopersici (FORL), Pythium ultimum, Rhizoctonia solani, Sclerotinia sclerotiorum, and Verticillium dahliae) on greenhouse cucumber and tomato. It reduced disease incidence significantly against P. ultimum and R. solani on both cucumber and tomato and against FORL on tomato. In addition, T. harzianum MAUL-20 stimulated plant growth of cucumber plants when amended to a substrate without plant pathogens. Its efficacy was compared to that of Rootshield™, a biofungicide based on Trichoderma harzianum KRL-AG2 registered in the USA. Its biocontrol potential was equivalent or superior to Rootshield™

Constraining the MSSM with universal gaugino masses and implication for searches at the LHC

Using a Markov chain Monte Carlo approach, we find the allowed parameter space of a MSSM model with seven free parameters. In this model universality conditions at the GUT scale are imposed on the gaugino sector. We require in particular that the relic density of dark matter saturates the value extracted from cosmological measurements assuming a standard cosmological scenario. We characterize the parameter space of the model that satisfies experimental constraints and illustrate the complementarity of the LHC searches, B-physics observables and direct dark matter searches for further probing the parameter space of the model. We also explore the different decay chains expected for the coloured particles that would be produced at LHC.Comment: 29 pages, 11 figure

Supersymmetry Without Prejudice

We begin an exploration of the physics associated with the general CP-conserving MSSM with Minimal Flavor Violation, the pMSSM. The 19 soft SUSY breaking parameters in this scenario are chosen so as to satisfy all existing experimental and theoretical constraints assuming that the WIMP is a conventional thermal relic, ie, the lightest neutralino. We scan this parameter space twice using both flat and log priors for the soft SUSY breaking mass parameters and compare the results which yield similar conclusions. Detailed constraints from both LEP and the Tevatron searches play a particularly important role in obtaining our final model samples. We find that the pMSSM leads to a much broader set of predictions for the properties of the SUSY partners as well as for a number of experimental observables than those found in any of the conventional SUSY breaking scenarios such as mSUGRA. This set of models can easily lead to atypical expectations for SUSY signals at the LHC.Comment: 61 pages, 24 figs. Refs., figs, and text added, typos fixed; This version has reduced/bitmapped figs. For a version with better figs please go to http://www.slac.stanford.edu/~rizz

The e+e- -> Z gamma gamma -> q q gamma gamma Reaction at LEP and Constraints on Anomalous Quartic Gauge Boson Couplings

The cross section of the process e^+ e^- -> Z \gamma\gamma -> qq \gamma \gamma is measured with 215 pb^-1 of data collected with the L3 detector during the final LEP run at centre-of-mass energies around 205 GeV and 207 GeV. No deviation from the Standard Model expectation is observed. The full data sample of 713 pb^-1, collected above the Z resonance, is used to constrain the coefficients of anomalous quartic gauge boson couplings to: -0.02 GeV^-2 < a_0/\Lambda^2 < 0.03 GeV^-2 and -0.07 GeV^-2 < a_c/\Lambda^2 < 0.05 GeV^-2, at 95% confidence level

Resistência do algodoeiro à ferrugem tropical potencializada pelo silício

Este trabalho teve como objetivo estudar o efeito do silício (Si) sobre componentes de resistência do algodoeiro à ferrugem tropical causada por Phakopsora gossypii. Plantas das cultivares BRS Buriti e FM 993 cresceram em solução nutritiva contendo zero (-Si) ou 2 mmol Si L- 1 (+Si). A maior concentração foliar de Si aumentou o período de incubação e o período latente em 9% e 14,3%, respectivamente, reduziu a área pustular, a área abaixo da curva de progresso da ferrugem e a área abaixo da curva de progresso da área da pústula em 27,5%, 36% e 22%, respectivamente. Nas plantas das cultivares BRS Buriti e FM 993 supridas com Si houve redução no número de pústulas em 70% e 30% e no número de urédias em 40,3% e 19,5%, respectivamente. A concentração de compostos fenólicos nas plantas da cultivar BRS Buriti supridas com Si aumentou até os 10 dai e, para a cultivar FM993, até os 30 dai. A concentração de derivados da lignina-ácido tioglicólico aumentou depois dos 20 dai para as duas cultivares supridas com Si. Atividade da peroxidas e aumentou até os 25 dai e os 10 dai para as plantas das cultivares BRS Buriti e FM 993 supridas com Si, respectivamente. A atividade da quitinase aumentou até 10 dai para as plantas da cultivar BRS Buriti e aos 10 e 20 dai para as plantas da cultivar supridas com Si. A atividade da glucanase aumentou até os 10 dai para as plantas da cultivar BRS Buriti supridas com Si e até os 20 dai para as plantas da cultivar FM 993 supridas com Si. Em conclusão, o suprimento de Si contribuiu para aumentar a resistência do algodoeiro à ferrugem devido à maior atividade das enzimas de defesa

Histochemical aspects of wheat resistance to leaf blast mediated by silicon

Blast, caused by Pyricularia oryzae, has become a significant disease threat to wheat (Triticum aestivum L.) in Brazil. This study aimed to investigate at the histochemical level if silicon (Si) could enhance the production of flavonoids in the leaves of wheat plants in response to P. oryzae infection. Plants from the Aliança cultivar, which are susceptible to blast, were grown in hydroponic cultures containing 0 (-Si) or 2 mM of Si (+Si) and inoculated by spraying a conidial suspension of P. oryzae (1 × 105 conidia mL−1) on all adaxial leaf surfaces of plants at 60 days after emergence (growth stage 65). The fourth and fifth leaves of each plant were used to evaluate blast severity at 24, 36, 48, 72 and 96 h after inoculation (hai). At 96 hai, leaves were collected from plants to determine the foliar Si concentration. For cytological observations, leaf samples were randomly collected from the fourth and fifth leaves of each plant at 72 hai. The foliar Si concentration was higher in +Si plants (36 g kg−1) in comparison to -Si plants (2.6 g kg−1). This increased Si concentration was correlated with reduced fungal growth inside the epidermal cells and the development of blast symptoms on leaves. Strong fluorescence, which is an indication of the presence of flavonoids, was detected in the leaf cells of +Si plants using Neu’s and Wilson's reagents. A novel item of evidence is that, at the histochemical level, Si is involved in the potentiation of the biosynthetic pathway of flavonoids that increases wheat resistance to blast

Addressing climate change with behavioral science:A global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions' effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior-several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people's initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors.</p

Study of the e+e- -> Z gamma gamma -> q q~ gamma gamma Process at LEP

The process e^+e^- -> Z gamma gamma -> q q~ gamma gamma is studied in 0.5 fb-1 of data collected with the L3 detector at centre-of-mass energies between 130.1 GeV and 201.7 GeV. Cross sections are measured and found to be consistent with the Standard Model expectations. The study of the least energetic photon constrains the quartic gauge boson couplings to -0.008 GeV-2 < a_0/\Lambda^2 < 0.005 GeV-2 and -0.007 GeV-2 < a_c/\Lambda^2 < 0.011 GeV-2, at 95% confidence level