The microbial ecology of a sustainable, long-term lentil-wheat rotation

Non-Peer Reviewe

Seasonal variation in the soil microbial community in wheat-growing soil and influence of C, N, and P inputs

Non-Peer ReviewedIt has long been know that N and P fertilization increases plant growth and yield, but the impact of fertilization on soil microorganisms has rarely been considered. Long-term plots (36-year old) under fallow-wheat-wheat (F-W-W) rotations with no P or no N fertilization, or normally fertilized, and plots receiving low C inputs due to frequent fallow (F-W rotation) were used to define the impact of C, N and P on the seasonal variation of the soil microbial communities in the fallow-after-wheat or the wheat-after-fallow phases of the rotations. The soil was sampled on June 8, July 4, August 5 and September 16, in 2003. There was no significant (P≤ 0.05) time by treatment interactions. Populations of bacteria, arbuscular mycorrhizal (AM) fungi and saprophytic fungi, as estimated by phospholipids fatty acid (PLFA) indicators, were strongly reduced on July 4th, a date corresponding to rapid plant growth. Sporulation of fungal saprobes was enhanced at that date, as indicated by the neutral lipid fatty acid (NLFA) to PLFA fraction ratio of the fatty acid C18:2. It appears that a competition for resources exists between soil microorganisms and wheat, at least in July at the time of active crop growth. While P availability had little effect on soil microorganisms, absence of N fertilization increased sporulation in AM and saprophytic fungi. In spite of the biotrophic1 nature of AM fungi, C input in the form of infrequent fallow or presence of living wheat plant favoured the partitioning of fatty acids into reserve lipid i.e., NLFA

Rhizobium inoculant formulation and placement in lentil and chickpea in the semiarid Canadian prairies

Non-Peer ReviewedLentil and chickpea are the major pulse crops grown in western Canada, but little is known about the responses of these annual legumes to rhizobium inoculant formulation, placement, and their interaction to fertilizers under semiarid environments. A field study was conducted from 1999 to 2002 on a medium-textured soil at Swift Current and on a heavy clay soil at Stewart Valley, both in Saskatchewan. The objectives were to (i) determine the effects of rhizobium inoculation and fertilization on nodule formation, N2-fixation, and their impacts on growth, yield, and seed quality in chickpea and lentil, and (ii) develop recommendations for optimizing rhizobium inoculation, P-solublizing inoculation, and fertilizer N and P application for direct-seeding of chickpea and lentil with 1-, 2-, and 3-tank delivery systems. The results of the six site-years showed that use of rhizobium inoculation increased seed yield by 35% for desi, 7% for kabuli, and 23% for lentil. Inoculation reduced desi plant population by 10%, but not in kabuli or lentil. Granular inoculant increased yield by 7% in chickpea and 8% in lentil, compared to peat-based powder inoculant. Placement of granular inoculant (seed-row vs side-banding) had the same effect in all three pulses. Starter-N and starter-P at a rate of 15 kg ha-1 each had a marginal effect on plant growth and seed yield, but a higher rate of P (34 kg P2O5 ha-1) increased kabuli seed size. Chickpea and lentil did not show any response to Penicillium bilaii (fungus contained in the products JumpStart® and TagTeam®) under the semiarid growing conditions

Microbial community structure under various wheat-based cropping systems

Non-Peer ReviewedThe effects of cropping systems on soil biological quality are slow to develop. We sampled the soil of a 36-year old long-term experiment established on an Orthic Brown Chernozem, at Swift Current SK, in the fall of 2003, to define the long-term impact of 10 cropping systems on soil biological quality. Numerous variables related to soil function - soil pH, organic C (SOC), moisture, enzymatic activities, available N, P, and S - and soil community structure - phospholipid fatty acids (PLFA) indicators of fungal saprobes, arbuscular mycorrhizal fungi and bacterial groups - were used to describe soil quality. Soils under different cropping systems had become distinct, as revealed by discriminant analyses. Variations in SOC, and pH were most influential in discriminating the soils. SOC varied from 2.38% under continuous wheat to 1.81% under a fallow-wheat rotation. pH went from 6.55 under fallow-wheat-wheat receiving no P-fertilizer, to 4.89, under chemical fallow – fall rye – wheat. Absence of fallow under normal fertilization increased SOC and decreased soil pH. Variations in SOC and pH were concurrent with variations in microbial community structure. Enhanced AM fungi abundance under low soil P, could compensate for the large soil P depletion created by 36 years without P fertilizer, in a fallow-wheat-wheat rotation, and P-fertilized and non-P-fertilized plots produced similar yields. The season of 2003 was dryer than normal and it remains to be seen if AM fungi can compensate for low soil available P when soil moisture is abundant

Differentiation of type A foot-and-mouth disease virus subtypes by double-and radial-immunodiffusion analysis.

Para clasificar el virus de la enfermedad de las patas y boca del ganado y reconocer el subtipo, se examinaron cuatro subtipos del virus FMDV (Foot and Mouth Disease Virus) así: A-12, A-24, A-31 y A-32. Si la identidad parcial se obtiene bajo condiciones de campo se indica un nuevo subtipo y deberá ser examinado en mayor detalle. La aplicabilidad de la técnica convencional de inmunodifusión radial para diferenciar subtipos de FMDV fue examinada y probada con antisueros por cada cuatro subtipos de virus para reacciones homólogas y heterogamas. Fueron evidentes las diferencias en apariencia de los anillos formados en el precipitado por sistemas homólogos y heterogamos. Los estimativos de la cantidad de anticuerpos precipitados por estos sistemas, se determinaron asumiendo un valor común (anillo-ración masa), la cual representa la masa inicial de anticuerpo dentro del anillo para la masa de antígenos usados en la fuente. Todos los antisueros contienen gran cantidad de anticuerpos que reaccionan con virus homólogos más que con virus heterogamos. Se hizo un rango tentativo antigénico en el cual los subtipos A-31 y A-32 estuvieron a los extremos de la lista de ordenamiento con subtipos A-24 y A-12 en una posición intermedia así: A-31, A-24, A-12 y A-32. Mientras la doble inmunodifusión permite la diferenciación de estos subtipos, el método SRID (Single Radial Inmunodiffusion Determinations) proporciona estimaciones cuantitativa

Respuesta de cobayos a la inoculación con cepas New Jersey e Indiana del virus de la estomatitis vesicular.

Con el ánimo de establecer un método útil para clasificar aislamientos virales, se estudió mediante inoculación en cobayos la virulencia de varias cepas de los virus de New Jersey (NJ) e Indiana (Ind.). Se utilizaron como marcadores, el desarrollo de vesículas primarias en el sitio de inoculación, el correspondiente período de inoculación y el desarrollo de vesículas secundarias. En este estudio fueron utilizados cobayos de diferentes edades, sexo y bioterío. Los cabayos de cinco meses fueron más susceptibles al virus Ind. que los de dos meses. Los resultados con el virus NJ fueron incosistentes, la respuesta primaria fué màs prevalente en cobayos de cinco meses y la frecuencia de lesiones secundarias fué mayor en cobayos de dos meses. Los cobayos hembras fueron más susceptibles al virus NJ. Ciertas cepas del virus Ind. que generalizaron en cobayos hembras jóvenes, no generalizaron en machos jóvenes. Machos del bioterío A fueron más susceptibles que los del bioterío B, sobre la de base de un período de incubación primario más corto. El virus NJ generalizó sólo en hembras de la colonia B. Con los resultados de este trabajo se concluye que no es posible clasificar las cepas de cada uno de los virus por virulencia. Se observó alguna correlación entre la virulencia de algunas cepas de NJ y de Ind. para ratones y virulencia para cobayos de dos meses de eda

Influence of a Random Telegraph Process on the Transport through a Point Contact

We describe the transport properties of a point contact under the influence of a classical two-level fluctuator. We employ a transfer matrix formalism allowing us to calculate arbitrary correlation functions of the stochastic process by mapping them on matrix products. The result is used to obtain the generating function of the full counting statistics of a classical point contact subject to a classical fluctuator, including extensions to a pair of two-level fluctuators as well as to a quantum point contact. We show that the noise in the quantum point contact is a sum of the (quantum) partitioning noise and the (classical) noise due to the two-level fluctuator. As a side result, we obtain the full counting statistics of a quantum point contact with time-dependent transmission probabilities.Comment: 8 pages, 2 figure; a new section about experiments and a figure showing the crossover from sub- to superpoissonian noise have been adde

Towards Solving QCD - The Transverse Zero Modes in Light-Cone Quantization

We formulate QCD in (d+1) dimensions using Dirac's front form with periodic boundary conditions, that is, within Discretized Light-Cone Quantization. The formalism is worked out in detail for SU(2) pure glue theory in (2+1) dimensions which is approximated by restriction to the lowest {\it transverse} momentum gluons. The dimensionally-reduced theory turns out to be SU(2) gauge theory coupled to adjoint scalar matter in (1+1) dimensions. The scalar field is the remnant of the transverse gluon. This field has modes of both non-zero and zero {\it longitudinal} momentum. We categorize the types of zero modes that occur into three classes, dynamical, topological, and constrained, each well known in separate contexts. The equation for the constrained mode is explicitly worked out. The Gauss law is rather simply resolved to extract physical, namely color singlet states. The topological gauge mode is treated according to two alternative scenarios related to the In the one, a spectrum is found consistent with pure SU(2) gluons in (1+1) dimensions. In the other, the gauge mode excitations are estimated and their role in the spectrum with genuine Fock excitations is explored. A color singlet state is given which satisfies Gauss' law. Its invariant mass is estimated and discussed in the physical limit.Comment: LaTex document, 26 pages, one figure (obtainable by contacting authors). To appear in Physical. Review

A preliminary investigation of the water use efficiency of sweet sorghum for biofuel in South Africa

Sweet sorghum (Sorghum bicolor (L.) Moench) has been recognized globally as a potential biofuel crop for ethanol production. Sweet sorghum is a drought-tolerant crop that is widely adapted to different environmental growing conditions. The aim of this study was to determine the water use efficiency (utilisable yield per unit amount of water used) of drip-irrigated sweet sorghum (variety Sugargraze) under two different climatic conditions in South Africa. The sweet sorghum trials were conducted at Ukulinga research farm (University of KwaZulu-Natal, Pietermaritzburg) and Hatfield experimental farm (University of Pretoria, Pretoria), South Africa. Field trials were conducted in two successive seasons, viz., 2010/11 and 2011/12. Seasonal water use was estimated using eddy covariance and surface renewal methods. Fresh and dry aboveground biomass yield, stalk yield and stalk Brix % were measured at final harvest. Theoretical ethanol yield was calculated from fresh stalk yield and Brix %. Water use for the two growing seasons was 415 mm at Ukulinga and 398 mm at Hatfield. The ethanol water use efficiency (WUE) values for the sweet sorghum at Ukulinga were 0.27 and 0.60 L∙m-3 for 2010/11 and 2011/12 growing seasons, respectively. The ethanol WUE estimate of the sweet sorghum at Hatfield was 0.53 L∙m-3 for the 2010/11 season and 0.70 L∙m-3 for the 2011/12 growing season. WUE estimates of the sweet sorghum crop were higher for Hatfield compared to Ukulinga research farm. The results from this study showed that the WUE of sweet sorghum was sensitive to plant density. The WUE values confirm that sweet sorghum has high WUE under different climatic conditions.The research presented in this paper forms part of a solicited research project (Water use of cropping systems adapted to bio-climatic regions in South Africa and suitable for biofuel production) that was initiated by the Water Research Commission (WRC) of South Africa in Key Strategic Area on Water Utilisation in Agriculture).Water Research Commission (WRC) of South Africahttp://www.wrc.org.zaam2016Plant Production and Soil Scienc

The Large Magellanic Cloud and the Distance Scale

The Magellanic Clouds, especially the Large Magellanic Cloud, are places where multiple distance indicators can be compared with each other in a straight-forward manner at considerable precision. We here review the distances derived from Cepheids, Red Variables, RR Lyraes, Red Clump Stars and Eclipsing Binaries, and show that the results from these distance indicators generally agree to within their errors, and the distance modulus to the Large Magellanic Cloud appears to be defined to 3% with a mean value of 18.48 mag, corresponding to 49.7 Kpc. The utility of the Magellanic Clouds in constructing and testing the distance scale will remain as we move into the era of Gaia.Comment: 23 pages, accepted for publication in Astrophysics and Space Science. From a presentation at the conference The Fundamental Cosmic Distance Scale: State of the Art and the Gaia Perspective, Naples, May 201