Effects of soil compaction, temperature, and moisture on the development of the Fusarium root rot complex of pea in southwestern Ontario

Le pourridié fusarien du pois (Fusarium spp.) constitue un complexe affecté par la compaction, la température et l'humidité du sol. L'effet de ces facteurs sur la gravité des pourritures fusariennes et sur la croissance du pois (Pisum sativum) a été étudié en environnement contrôlé. Le sol utilisé, issu d'un champ ayant des antécédents connus de la maladie, était infesté par les agents pathogènes qui causent le pourridié fusarien. Plusieurs niveaux de chaque facteur ont été utilisés. En environnement contrôlé, les résultats ont montré qu'un accroissement de la densité apparente du sol dû à la compaction augmentait significativement l'incidence et l'intensité du pourridié fusarien et réduisait de façon appréciable le poids frais des plantes de pois. L'augmentation graduelle de la température du sol de 10 à 30°C a résulté en un accroissement de l'intensité des pourritures racinaires et de l'expression des symptômes foliaires. À un niveau d'humidité du sol équivalant à 70% de la capacité au champ, les plantes de pois avaient une intensité de pourridié fusarien plus faible que celles cultivées dans un sol à 100, 50 ou 25% de la capacité au champ. Les plantes de pois soumises à des inondations temporaires ont présenté une incidence et une intensité de pourritures racinaires accrues lorsque la durée de l'inondation est passée de 1 à 5 jours.The pea root rot complex (Fusarium spp.) is known to be affected by compaction, temperature, and moisture of the soils. This paper reports the effects of these factors on root rot severity and pea (Pisum sativum) growth tested in a controlled environment, using a Fusarium-infested soil collected from a field with a severe root rot history. For each factor, several increments were used. The results showed that in a controlled environment, an increase in soil bulk density due to compaction significantly increased root rot incidence and disease severity, and drastically reduced the fresh weight of pea plants. Stepwise increases in soil temperature from 10 to 30°C resulted in increases in estimated root rot severity and foliar symptom expression. Pea plants grown in soil moisture at 75% of field capacity had significantly lower Fusarium root rot incidence and severity than those grown in soil at 100%, 50% or 25% of field capacity. Pea plants subjected to temporary flooding exhibited an increased root rot incidence and severity as the duration of flooding increased from 1 to 5 d

Anthracnose

Bean anthracnose, caused by the fungus Colletotrichum lindemuthianum, is a worldwide disease in susceptible var. grown in locations with cool to moderate temp. and with a high RH. It can appear anywhere in the plant. Losses can be up to 100 percent when severely infected seed is planted. For efficient disease control, the production of disease-free seed, crop rotations, utilization of adequate chemical products, and the use of resistent var. are recommended. The symptoms and damage caused by the disease are illustrated in color. (CIAT)La antracnosis del frijol, causada por el hongo Colletotrichum lindemuthianum, es una enfermedad que se presenta en todo el mundo en las var. susceptibles establecidas en localidades con temp. moderadas-frias y con alta HR ambiental. Puede aparecer en cualquier parte de la planta. Las perdidas pueden ser del 100 por ciento cuando se siembra semilla severamente infectada. Para un buen control de la enfermedad se recomiendan la produccion de semilla libre del patogeno, rotacion de cultivos, utilizacion de productos quimicos adecuados y var. resistentes. Se ilustran a color los sintomas y danos causados por la enfermedad. (CIAT

Dimensional Crossover of Dilute Neon inside Infinitely Long Single-Walled Carbon Nanotubes Viewed from Specific Heats

A simple formula for coordinates of carbon atoms in a unit cell of a single-walled nanotube (SWNT) is presented and the potential of neon (Ne) inside an infinitely long SWNT is analytically derived under the assumption of pair-wise Lennard-Jones potential between Ne and carbon atoms. Specific heats of dilute Ne inside infinitely long (5, 5), (10, 10), (15, 15) and (20, 20) SWNT's are calculated at different temperatures. It is found that Ne inside four kinds of nanotubes exhibits 3-dimensional (3D) gas behavior at high temperature but different behaviors at low temperature: Ne inside (5, 5) nanotube behaves as 1D gas but inside (10, 10), (15, 15), and (20, 20) nanotubes behaves as 2D gas. Furthermore, at ultra low temperature, Ne inside (5, 5) nanotube still displays 1D behavior but inside (10, 10), (15, 15), and (20, 20) nanotubes behaves as lattice gas.Comment: 10 pages, 5 figure

Skeletal Shape Correspondence Through Entropy

We present a novel approach for improving the shape statistics of medical image objects by generating correspondence of skeletal points. Each object's interior is modeled by an s-rep, i.e., by a sampled, folded, two-sided skeletal sheet with spoke vectors proceeding from the skeletal sheet to the boundary. The skeleton is divided into three parts: the up side, the down side, and the fold curve. The spokes on each part are treated separately and, using spoke interpolation, are shifted along that skeleton in each training sample so as to tighten the probability distribution on those spokes' geometric properties while sampling the object interior regularly. As with the surface/boundary-based correspondence method of Cates et al., entropy is used to measure both the probability distribution tightness and the sampling regularity, here of the spokes' geometric properties. Evaluation on synthetic and real world lateral ventricle and hippocampus data sets demonstrate improvement in the performance of statistics using the resulting probability distributions. This improvement is greater than that achieved by an entropy-based correspondence method on the boundary points

Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and νp nucleosynthesis processes

© 2018 The Authors. Published by Elsevier B.V. This manuscript is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND 4.0). For further details please see: https://creativecommons.org/licenses/by-nc-nd/4.0/Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of 82Zr and 84Nb were measured for the first time with an uncertainty of ∼10 keV, and the masses of 79Y, 81Zr, and 83Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low α separation energies for neutron-deficient Mo and Tc isotopes, making the formation of Zr–Nb cycle in the rp-process unlikely. The new proton separation energy of 83Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus 84Sr relative to the neutron-deficient molybdenum isotopes in the previous νp-process simulations.Peer reviewe

Solar Wind Turbulence and the Role of Ion Instabilities

International audienc

Resistência a Septoria lycopersici em espécies de Solanum (Secção Lycopersicon) e em progênies de S. lycopersicum × S. peruvianum

Septoria leaf spot (Septoria lycopersici) is one of the major fungal diseases of tomatoes (Solanum lycopersicum) in tropical and subtropical regions with humid climates and/or in areas cultivated under sprinkler irrigation systems. Sources of resistance have been found in accessions of Solanum (section Lycopersicon) species. However, many of the described sources are not effective under Brazilian conditions. The objective of this work was to evaluate wild and cultivated Solanum (section Lycopersicon) germplasm to S. lycopersici isolates. A collection of 124 accessions was initially evaluated under greenhouse conditions. Ten accessions were highly resistance (HR), whereas 33 were classified as having a resistant (R) response to S. lycopersici isolates. Field evaluation was also conducted with a sub-set of accessions identified as either HR or R in the greenhouse experiment. This field evaluation confirmed greenhouse tests and indicated the presence of some potential sources of rate-reducing resistance. One highly resistant and eight resistant S. habrochaites accessions were identified as being resistant under both conditions, confirming that this wild species is one of the most promising sources of resistance to S. lycopersici. Five new sources with high levels of resistance were found in S. peruvianum accessions (PI-306811, CNPH-1036, LA-1910, LA-1984 and LA-2744). One accession derived from an interspecific cross between S. lycopersicum and S. peruvianum was also found to be highly resistant and might be useful to introgress resistance factors from this wild species into cultivated tomato germplasm. However, additional breeding efforts will be necessary to introgress into the cultivated tomato the resistance factors identified in other S. peruvianum accessions due to the presence of natural crossing barriers between the two species.A mancha-de-septória (Septoria lycopersici) é importante doença fúngica do tomateiro (Solanum lycopersicum) em áreas tropicais e subtropicais com alta umidade ou quando esta hortaliça é cultivada sob irrigação por aspersão. Fontes de resistência têm sido encontradas em germoplasma de Solanum (secção Lycopersicon). No entanto, muitas das fontes descritas não funcionam nas condições brasileiras. Avaliou-se uma coleção de germoplasma de tomate cultivado e selvagem (Solanum secção Lycopersicon) visando identificar novas fontes de elevada resistência. Uma coleção de 124 acessos foi inicialmente avaliada sob condições de casa de vegetação. Somente dez acessos foram classificados como altamente resistentes e 33 foram classificados como resistentes. Um ensaio de campo foi também conduzido com um subconjunto de acessos promissores identificados no primeiro experimento. Foi confirmada a resposta da maioria dos acessos avaliados em casa de vegetação e indicou a presença de fontes de resistência capazes de reduzir a taxa de progresso da doença. Um acesso de S. habrochaites com elevada resistência e oito acessos resistentes foram identificados, confirmando que esta espécie representa uma das mais promissoras fontes de genes de resistência a S. lycopersici. Cinco novas fontes com elevados níveis de resistência foram identificadas em acessos da espécie S. peruvianum (PI-306811, CNPH-1036, LA-1910, LA-1984 e LA-2744). Um acesso, derivado de cruzamento interespecífico entre S. lycopersicum e S. peruvianum também mostrou-se altamente resistente e poderá ser útil na introgressão deste(s) gene(s) em germoplasma de tomateiro cultivado. No entanto, esforços adicionais de melhoramento serão necessários para transferir para o tomateiro cultivado os fatores de resistência identificados em outros acessos de S. peruvianum, uma vez que existem barreiras naturais de cruzamentos entre estas duas espécies

Bounds and phase diagram of efficiency at maximum power for tight-coupling molecular motors

The efficiency at maximum power (EMP) for tight-coupling molecular motors is investigated within the framework of irreversible thermodynamics. It is found that the EMP depends merely on the constitutive relation between the thermodynamic current and force. The motors are classified into four generic types (linear, superlinear, sublinear, and mixed types) according to the characteristics of the constitutive relation, and then the corresponding ranges of the EMP for these four types of molecular motors are obtained. The exact bounds of the EMP are derived and expressed as the explicit functions of the free energy released by the fuel in each motor step. A phase diagram is constructed which clearly shows how the region where the parameters (the load distribution factor and the free energy released by the fuel in each motor step) are located can determine whether the value of the EMP is larger or smaller than 1/2. This phase diagram reveals that motors using ATP as fuel under physiological conditions can work at maximum power with higher efficiency ($>1/2$) for a small load distribution factor ($<0.1$).Comment: 5 pages, 4 figure

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication