Can crop disease control cope with climate change?

Crop yields need to increase by at least 70% over the next 35 years in order to meet the global demands for food due to the increasing population and changing dietary preferences towards meat and dairy products in developing nations. Climate change threatens food security because pests and diseases that limit crop productivity are all sensitive to climate change and especially to more frequent extreme weather events. A more variable climate will mean greater uncertainty for crop yields because crop development stages, e.g. when reproductive organs such as flowers and seeds are produced, are especially vulnerable to short periods of extreme temperature or drought. For instance, Europe experienced an extreme climate event during the summer of 2003 when temperatures were ca. 6°C higher and rainfall was ca. 300 mm less than the long-term mean values. One impact of this summer was a record crop yield decrease of ca. 36% below average yield in Italy for maizePeer reviewedFinal Accepted Versio

Analyse diskreter Flüssigkeits-Gasströmungen mit optischen Fasersensoren

Im Rahmen des Graduiertenkollegs GRK358 mit dem Thema "Optische Messmethoden in den Ingenieurwissenschaften" wurde am Lehrstuhl für Mechanische Verfahrenstechnik an der Dortmund Universität eine faseroptische Messtechnik zur Charakterisierung von Mehrphasenströmungen entwickelt. Die Technik basiert auf der Einkopplung von Laserlicht in eine Faser, wobei die vom benetzenden Fluid abhängige Reflexion des Lichts am Faserende gemessen wird. Durch die Auswertung der Lichtreflexion kann der Phasenwechsel des Fluids am Fasersensor bestimmt werden. Zuerst wurden hier auf das Faserende aufprallende Wassertropfen mit einer einzelnen Faser untersucht. Dies führt zu einem komplexen Lichtsignal. Dazu wurden theoretische Berechnungen für die Lichtreflexionen am Sensorende durchgeführt und diese mit den Ergebnissen aus Abtropf- und Aufprallversuchen verglichen. Darauf aufbauend wurde die Geschwindigkeit der Wassertropfen mittels zweier in Bewegungsrichtung versetzter Fasern bestimmt. Die gemessenen Geschwindigkeiten der Phasengrenzen wurden durch Aufnahmen mit einer Hochgeschwindigkeitskamera überprüft. Im zweiten Abschnitt wurden die Fasersensoren für die Charakterisierung von Schäumen eingesetzt. Mit dem Fasersensor kann die Grenze zwischen dem eigentlichen Schaum und der Blasenströmung einfach bestimmt werden. Durch eine zusätzliche Faser kann die Grenze zwischen dem Schaum und der Flüssigkeit erfasst werden, in der eine hoch beladende Blasenströmung auftritt. Die Schaumgeschwindigkeit kann durch die Kombination von zwei Fasern gemessen werden. Mit Hilfe des Korrelationsverfahrens wurden die Messdaten ausgewertet. Hiermit können nicht nur die Schaumgeschwindigkeiten, sondern auch die durchschnittlichen Blasengrößen bestimmt werden. Für die Berechnung der Blasengröße wurde ein Korrekturfaktor k eingeführt. Er berücksichtigt die zufällige Positionierung innerhalb von der als sphärisch angenommener Blasen. Nach der Korrektur der Messergebnisse für die Blasengröße besteht gute Übereinstimmung mit den Fotos der Kamera. Außerdem wurde die Gasbeladung des Kugelschaums bzw. des chaotischen Mischbereichs in der Flüssigkeit über eine spezielle Auswertungsmethode berechnet.Within the graduate colleg "GRK 358" at the chair of mechanical process engineering at Dortmund University a fiber-optic measuring technique was developed for the characterisation of the multiphase flows. The laser light is injected into a fiber, in which the reflection of the light at the end of the fiber is measured, which depends on the fluid in contact. The phase change of the fluid at the fiber sensor can be determined by the analysis of the light reflection signals. At first, water drops were examined, impinging onto at the end of a single fiber sensor. A complex light signal is generated. Theoretical calculations for the light reflection at the end of the sensor were carried out. Compared to the results of experiments the signals of impingement experiments of the water drops were explained. With this knowledge the speed of water drops was measured by use of a combination of two fibers. The measured speed of the phase boundary by the fiber sensors was validated by the photographs from a high-speed camera. The results of both measuring methods show good agreement. In the second section the fiber sensors were used for the characterisation of foams. The interface between the foam and the liquid can be simply determined with one fiber sensor. In case of a highly loading gas dispersion in the liquid the interface between the foam and the liquid the application of a second fiber is successful. The foam speed can be measured by the use of the combination of two fibers. The measured data from the two fibers were evaluated by means of the cross correlation method. Not only the foam speeds, but also the average bubble sizes of the foam can be determined from these signals. A correction faktor k was introduced for the calculation of the bubble size. After correction with this factor, the bubble size agrees well with the bubble size in photos from a camera. In addition, the gas loading of wet foams and gas loading of the gas dispersion in the liquid can be calculated with a special evaluation method

Fluctuations in Number of Cercospora beticola Conidia in Relationship to Environment and Disease Severity in Sugar Beet

All content of Phytopathology is open access without restriction 12 months after publicationCercospora leaf spot, caused by Cercospora beticola, is the most damaging foliar disease of sugar beet in Minnesota (MN) and North Dakota (ND). Research was conducted to characterize the temporal progression of aerial concentration of C. beticola conidia in association with the environment and disease severity in sugar beet. In 2003 and 2004, volumetric spore traps were placed within inoculated sugar beet plots to determine daily dispersal of conidia at Breckenridge, MN, and St. Thomas, ND. Plots were rated weekly for disease severity. At both locations, conidia were first collected in early July 2003 and late June in 2004. Peaks of conidia per cubic meter of air were observed with maxima in late August 2003 and in early September 2004 at both locations. Peaks of airborne conidium concentration were significantly correlated with the average temperature of daily hours when relative humidity was greater than 87%. Weekly mean hourly conidia per cubic meter of air was significantly (P <0.01) associated with disease severity during both years and across locations. This study showed that C. beticola conidial numbers may be used to estimate potential disease severity that, with further research, could be incorporated in a disease forecasting model to rationalize Cercospora leaf spot management.Peer reviewe

Grassland futures in Great Britain – Productivity assessment and scenarios for land use change opportunities

This is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).To optimise trade-offs provided by future changes in grassland use intensity, spatially and temporally explicit estimates of respective grassland productivities are required at the systems level. Here, we benchmark the potential national availability of grassland biomass, identify optimal strategies for its management, and investigate the relative importance of intensification over reversion (prioritising productivity versus environmental ecosystem services). Process-conservative meta-models for different grasslands were used to calculate the baseline dry matter yields (DMY; 1961–1990) at 1 km2 resolution for the whole UK. The effects of climate change, rising atmospheric [CO2] and technological progress on baseline DMYs were used to estimate future grassland productivities (up to 2050) for low and medium CO2 emission scenarios of UKCP09. UK benchmark productivities of 12.5, 8.7 and 2.8 t/ha on temporary, permanent and rough-grazing grassland, respectively, accounted for productivity gains by 2010. By 2050, productivities under medium emission scenario are predicted to increase to 15.5 and 9.8 t/ha on temporary and permanent grassland, respectively, but not on rough grassland. Based on surveyed grassland distributions for Great Britain in 2010 the annual availability of grassland biomass is likely to rise from 64 to 72 million tonnes by 2050. Assuming optimal N application could close existing productivity gaps of ca. 40% a range of management options could deliver additional 21 ∗ 106 tonnes of biomass available for bioenergy. Scenarios of changes in grassland use intensity demonstrated considerable scope for maintaining or further increasing grassland production and sparing some grassland for the provision of environmental ecosystem services.Peer reviewedFinal Published versio

Effectiveness of Rlm7 resistance against Leptosphaeria maculans (phoma stem canker) in UK winter oilseed rape cultivars

© 2018 The Authors. Plant Pathology published by John Wiley & Sons Ltd on behalf of British Society for Plant Pathology. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.The Rlm7 gene in Brassica napus is an important source of resistance for control of phoma stem canker on oilseed rape caused by the fungus Leptosphaeria maculans. This study shows the first report of L. maculans isolates virulent against Rlm7 in the UK. Leptosphaeria maculans isolates virulent against Rlm7 represented 3% of the pathogen population when cultivars with the Rlm7 gene represented 5% of the UK oilseed rape area in 2012/13. However, the Rlm7 gene has been widely used since then, representing >15% of the UK oilseed rape area in 2015/16. Winter oilseed rape field experiments included cultivars with the Rlm7 gene, with the Rlm4 gene or without Rlm genes and took place at five sites in the UK over four cropping seasons. An increase in phoma leaf spotting severity on Rlm7 cultivars in successive seasons was observed. Major resistance genes played a role in preventing severe phoma leaf spotting at the beginning of the cropping season and, in addition, quantitative resistance (QR) in the cultivars examined made an important contribution to control of phoma stem canker development at the end of the cropping season. Deployment of the Rlm7 resistance gene against L. maculans in cultivars with QR in combination with sustainable disease management practices will prolong the use of this gene for effective control of phoma stem canker epidemics.Peer reviewe

Evaluating Responses of Sugar Beet Cultivars to Fusarium Species in Greenhouse and Field Conditions

Fusarium yellows of sugar beet (Beta vulgaris L.) is becoming an important disease in Minnesota and North Dakota in the United States. One of the best ways to manage Fusarium yellows is to develop and use resistant cultivars. Responses of eight sugar beet cultivars to three Fusarium species were determined in the greenhouse and compared to the responses of the same eight cultivars grown in a field already infected by Fusarium yellows. There were significant and appreciable relationships between greenhouse and field studies for responses of eight sugar beet cultivars on Fusarium yellows. The estimated correlation coefficient for area under disease progress curve (AUDPC) between observations in fields and those in greenhouses was 0.987 (p<0.01). The mean AUDPC were significantly different among cultivars (p<0.01) in the greenhouse and in the field studies. Of the cultivars, Van der Have 46177 was the most susceptible, but Crystal R434 the most resistant. Crystal 820, Van der Have 66561, and Beta 4797R were resistant, and Beta 4818R, Seedex Magnum, and Hilleshog 2463Rz were moderately resistant. There was a strong negative relationship between the AUDPC and recoverable sucrose yield in the field experiments and the estimated coefficient of determination was 0.939 (p<0.01). It was concluded that greenhouse screening can act as a useful and reliable means to evaluate and select beet germplasms and/or accessions for resistance to Fusarium yellows.Peer reviewe

Optically discriminating carrier-induced quasiparticle band gap and exciton energy renormalization in monolayer MoS2

Optoelectronic excitations in monolayer MoS2 manifest from a hierarchy of electrically tunable, Coulombic free-carrier and excitonic many-body phenomena. Investigating the fundamental interactions underpinning these phenomena - critical to both many-body physics exploration and device applications - presents challenges, however, due to a complex balance of competing optoelectronic effects and interdependent properties. Here, optical detection of bound- and free-carrier photoexcitations is used to directly quantify carrier-induced changes of the quasiparticle band gap and exciton binding energies. The results explicitly disentangle the competing effects and highlight longstanding theoretical predictions of large carrier-induced band gap and exciton renormalization in 2D semiconductors

The multifunctional protein CI of potyviruses plays interlinked and distinct roles in viral genome replication and intercellular movement

BACKGROUND: The multifunctional cylindrical inclusion (CI) protein of potyviruses contains ATP binding and RNA helicase activities. As part of the viral replication complex, it assists viral genome replication, possibly by binding to RNA and unwinding the RNA duplex. It also functions in viral cell-to-cell movement, likely via the formation of conical structures at plasmodesmata (PD) and the interaction with coat protein (CP). METHODS: To further understand the role of CI in the viral infection process, we employed the alanine-scanning mutagenesis approach to mutate CI in the infectious full-length cDNA clone of Turnip mosaic virus (TuMV) tagged by green fluorescent protein. A total of 40 double-substitutions were made at the clustered charged residues. The effect of these mutations on viral genome amplification was determined using a protoplast inoculation assay. All the mutants were also introduced into Nicotiana benthamiana plants to assess their cell-to-cell and long-distance movement. Three cell-to-cell movement-abolished mutants were randomly selected to determine if their mutated CI protein targets PD and interacts with CP by confocal microscopy. RESULTS: Twenty CI mutants were replication-defective (5 abolished and 15 reduced), one produced an elevated level of viral genome in comparison with the parental virus, and the remaining 19 retained the same replication level as the parental virus. The replication-defective mutations were predominately located in the helicase domains and C-terminal region. All 15 replication-reduced mutants showed delayed or abolished cell-to-cell movement. Nine of 20 replication-competent mutants contained infection within single cells. Five of them distributed mutations within the N-terminal 100 amino acids. Most of replication-defective or cell-to-cell movement-abolished mutants failed to infect plants systemically. Analysis of three randomly selected replication-competent yet cell-to-cell movement-abolished mutants revealed that the mutated CI failed to form regular punctate structures at PD and/or to interact with CP. CONCLUSIONS: The helicase domain and C-terminal region of TuMV CI are essential for viral genome replication, and the N-terminal sequence modulates viral cell-to-cell movement. TuMV CI plays both interlinked and distinct roles in replication and intercellular movement. The ability of CI to target PD and interact with CP is associated with its functional role in viral cell-to-cell movement. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12985-015-0369-2) contains supplementary material, which is available to authorized users