Non‐target site SDHI resistance is present as standing genetic variation in field populations of Zymoseptoria tritici          下载免费PDF全文

Masao Yamashita  Bart Fraaije 《Pest management science》2018,74(3):672-681

BACKGROUND

A new generation of more active succinate dehydrogenase (Sdh) inhibitors (SDHIs) is currently widely used to control Septoria leaf blotch in northwest Europe. Detailed studies were conducted on Zymoseptoria tritici field isolates with reduced sensitivity to fluopyram and isofetamid; SDHIs which have only just or not been introduced for cereal disease control, respectively.

RESULTS

Strong cross‐resistance between fluopyram and isofetamid, but not with other SDHIs, was confirmed through sensitivity tests using laboratory mutants and field isolates with and without Sdh mutations. The sensitivity profiles of most field isolates resistant to fluopyram and isofetamid were very similar to a lab mutant carrying SdhC‐A84V, but no alterations were found in SdhB, C and D. Inhibition of mitochondrial Sdh enzyme activity and control efficacy in planta for those isolates was severely impaired by fluopyram and isofetamid, but not by bixafen. Isolates with similar phenotypes were not only detected in northwest Europe but also in New Zealand before the widely use of SDHIs.

CONCLUSION

This is the first report of SDHI‐specific non‐target site resistance in Z. tritici. Monitoring studies show that this resistance mechanism is present and can be selected from standing genetic variation in field populations. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

Modelling self-pruning and branch attributes for young Quercus robur L. and Fagus sylvatica L. trees     

Vincent Kint  Sebastian Hein  Matteo Campioli  Bart Muys 《Forest Ecology and Management》2010

The aim of this study was to develop statistical models for first order branchiness in young planted forest stands of pedunculate oak (Quercus robur L.) and European beech (Fagus sylvatica L.), and to give an ecological and silvicultural interpretation to these models. The reported models focus on the lower most-valuable stem part (i.e. until 6 m height), and cover different tree development classes to capture the development of branchiness over time. For each species 30 study plots were selected spread over two nearby forests in Flanders (northern Belgium), minimising site and genetic variability. Branches were counted on a total of 399 oak and 376 beech trees. On a subsample of 30 trees per species (one tree per plot), detailed non-destructive branch measurements were performed, yielding data for 555 oak and 438 beech branches. For both species, models for tree self-pruning (i.e. total branch number and dead branch portion), branch mortality and branch architecture (i.e. branch diameter and branch insertion angle) were built. A generalised linear mixed modelling approach was adopted. The models for total branch number and dead branch portion may be interpreted in terms of four processes contributing to self-pruning: (1) stand and tree development, (2) tree competitive status, (3) stand density and (4) site humidity. The reported models reveal similar self-pruning rates in oak and beech, but with different driving factors: early branch dying and slow shedding for oak and the other way around for beech. Mortality of individual branches is further determined by branch position and branch dimension. Branch diameter and branch insertion angle of both species are mainly related to branch cord length and relative branch position. All modelled effects are consistent with known ecological and ecophysiological processes. Silvicultural implications for stand establishment and early tree selection are discussed. The reported models can be used to fine-tune operational silvicultural choices for quality timber production. This is a first step towards the integration of branchiness models for oak and beech into forest growth simulators.  相似文献   

Optimization of Phosphorus Fertilizer in Supplemental Feed‐Fed Based Nile Tilapia (Oreochromis niloticus) Ponds          下载免费PDF全文

Moe Thidar Oo  A M Shahabuddin  Dhirendra P Thakur  Aye Aye Mon  Amararatne Yakupitiyage  Amrit N Bart  Ram C Bhujel  Jim S Diana 《Aquaculture Research》2015,46(12):2859-2870

An experiment was conducted in earthen ponds at the Asian Institute of Technology, Thailand to determine different phosphorus fertilizer dose effects on Nile tilapia production, water quality variables, nutrient utilization and cost‐benefit under supplemental feeding. Five phosphorus fertilization rates were used as treatments e.g. 100%, 75%, 50%, 25% and 0% of 7 kg P ha week^?1. Nitrogen fertilization rate was fixed at 28 kg N ha week^?1 for all the treatments. Sex‐reversed Nile tilapia were stocked at 3 fish m^?2, and 30% CP floating feed fed at 50% satiation feeding rate. Nutrient budget showed higher phosphorus fertilizer input resulted in higher phosphorus sink in the sediment. Mean weight, mean weight gain, daily weight gain and net yield were not significantly different among treatments (P > 0.05). Total Kjeldahl nitrogen, total phosphorus and soluble reactive phosphorus were significantly different among treatments. Economic analysis showed phosphorus fertilization resulted in positive net returns. Though the gross income was not affected by different fertilization rates, significantly lowest cost was found in the treatment using 25% phosphorus fertilizer. It can be concluded from the research that 25% phosphorus fertilization might be used as an alternative strategy of Nile tilapia pond culture in terms of economic return and nutrient loss in sediment.  相似文献   

<Emphasis Type="Italic">In planta</Emphasis> PCR-based detection of early infection of plant-parasitic nematodes in the roots: a step towards the understanding of infection and plant defence     

Syarifah Aisyafaznim Sayed Abdul Rahman  Zulqarnain Mohamed  Rofina Yasmin Othman  Rony Swennen  Bart Panis  Dirk De Waele  Serge Remy  Sebastien Christian Carpentier 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(3):343-351

The polyphagous obligate parasites Meloidogyne spp. devastate a wide range of crop plants including bananas and plantains. Their infestations impact agriculture worldwide. Therefore, an effective combating regime against this nematode species and an in-depth understanding of plant-nematode interaction are essential. Early detection of infection by visual inspection is not possible. This hampers early control strategy efforts and makes in-depth research of the early infection and plant defence unfeasible. A simple and robust in planta PCR-based nematode detection method is described here as the first crucial step. This PCR-based detection assay exploits the existence of the Internal Transcribed Spacer 1 (ITS 1) region of the ribosomal DNA (rDNA) gene family in the nematodes for early detection of nematode penetration into the roots. The results demonstrate that this detection assay is suitable to serve as a molecular screening tool for plant root diagnostic purposes.  相似文献   

Zinc distribution and speciation within rocket plants (Eruca vesicaria L. Cavalieri) grown on a polluted soil amended with compost as determined by XRF microtomography and micro-XANES     

Terzano R  Al Chami Z  Vekemans B  Janssens K  Miano T  Ruggiero P 《Journal of agricultural and food chemistry》2008,56(9):3222-3231

Zinc distribution and speciation within different organs (root, petiole, and leaf) of the edible plant Eruca vesicaria L. Cavalieri were determined using synchrotron microbeam X-ray techniques (XRF microtomography and mu-XANES) for plants grown in polluted soil with or without compost amendment. Data on soil derived from different extraction procedures and using mu-XANES analyses on rhizospheric soil indicated that compost amendment did not significantly influence the Zn speciation and availability in soil. However, major differences were observed within the plants. Plants grown in the presence of compost were able to partly block zinc immediately outside the root endodermis in the form of zinc-phytate, while a smaller Zn fraction was allowed to xylem transport as zinc-citrate. In the leaves, zinc was largely excluded from leaf cells, and about approximately 50% was in the form of phosphate precipitates, and the other 50% was complexed by cysteine and histidine residues. The reported data provide new information concerning the mechanisms of zinc tolerance in E. vesicaria L. Cavalieri, a very common edible plant in Mediterranean regions, and on the role of compost in influencing the molecular strategies involved in zinc uptake and detoxification.  相似文献   

Estimation of Fine Root Biomass of Alders Growing on Technosols Using Two Different Methods     

Bartłomiej Świątek  Marcin Chodak  Marcin Pietrzykowski 《Communications in Soil Science and Plant Analysis》2019,50(4):474-481

Fine roots play an important role in organic matter accumulation in reclaimed mine soils. However, estimation of the increment of fine root biomass is difficult and none of the existing methods is universal. The paper examined two methods for measurement of fine roots biomass increment (FRBI): i) with using the root-ingrowth core method (RIC) and ii) the monolith sampling method (MSC). The study was conducted under alder plantings (Alnus incana, A. glutinosa and A. viridis) introduced on technosols at a combustion waste disposal site and a former open-cast sand mine. The FRBI determined using MSC method was significantly lower (33–481 g m^?2 yr^?1) and less variable than the FRBI measured with RIC (85–2317 g m^?2 yr^?1). However, the results obtained with both methods were correlated (r = 0.70, P = 0,05). Consequently, MSC is better to qualitatively compare the habitats of tree species in terms of their ability to produce fine roots. However, in the initial soils where plants very often produce more fine roots, RIC seems to be more suitable. This method shows the actual ability of trees to produce roots in order to satisfy their life needs when acquiring a new habitat on reclaimed soils. Such information is particularly important in oligotrophic soils where nutrient deficiency may be balanced only by the efficient circulation and decomposition of organic matter (SOM) including the fine roots that die off after each growing season.  相似文献   

The effect of the introduction of Nile tilapia (Oreochromis niloticus,L.) on small indigenous fish species (mola,Amblypharyngodon mola,Hamilton; chela,Chela cachius,Hamilton; punti,Puntius sophore,Hamilton)     

Sultanul Arafin Shemeen Ahmad  Amrit N Bart  Yang Yi  James E Rakocy  James S Diana 《Aquaculture Research》2010,41(6):904-912

This is the first controlled experiment to quantify the effect of introduced tilapia on indigenous species. This experiment was conducted in small earthen ponds (100 m²) to assess the impact of mixed‐sex or all‐male Nile tilapia (Oreochromis niloticus) on small indigenous species (SIS) commonly found in south Asia, mola (Amblypharyngodon mola), chela (Chela cachius) and punti (Puntius sophore). Ponds were fertilized, then stocked with 0.56 fish m^?2 of water surface area in the mixed‐sex and all‐male tilapia treatments and 0.42 fish m^?2 in the treatment without tilapia. No additional nutritional inputs were applied after stocking. Treatments were: mixed‐sex tilapia with SIS, mono‐sex male tilapia with SIS and SIS without tilapia (control). All treatments were stocked with 14 fish per species. All species reproduced during the 21‐month culture duration. The number of recruits varied by species, Tilapia reproduced in greater numbers than SIS. Tilapia numbers at harvest were the highest (451 ± 25/100 m²) in the mixed‐sex treatment compared with mola (221 ± 22/100 m²), chela (94 ± 8/100 m²) and punti (100 ± 7/100 m²). The number of mola was higher (399 ± 33/100 m²) in the all‐male tilapia treatment. There was reduction in the number of mola and chela in the treatment containing mixed‐sex tilapia. Gut content analysis combined with water sampling revealed that all fish species fed selectively. Significant interspecies dietary overlap was found between Nile tilapia and SIS and among SIS. Thus, there is potential for tilapia to compete with indigenous fish species when space and other resources are limiting, but a longer duration study with varying level of management is needed to determine how successfully tilapia competes with locally adapted SIS.  相似文献   

Ascorbic acid concentration in Cv. conference pears during fruit development and postharvest storage     

Franck C  Baetens M  Lammertyn J  Verboven P  Davey MW  Nicolaï BM 《Journal of agricultural and food chemistry》2003,51(16):4757-4763

L-ascorbic acid (L-AA) concentration changes during the development of cv. Conference pears and the influence of postharvest handlings (gas condition, cooling rate, cooling duration) on L-AA breakdown were studied. L-AA concentration fluctuates in young fruits, remains stable during fruit maturation, and starts to decline 1 week before commercial harvest. The most rapid decrease in L-AA concentration was found during immediate controlled atmosphere. During short-term storage, only the gas condition was found to influence L-AA breakdown; no significant difference between gradually or immediately cooled pears was determined. Under air conditions, both cooling strategies did not differ from the L-AA breakdown in pears allowed to ripen on the tree up until 3 weeks after the optimal harvest date. During long-term storage, the cooling duration (1-3 weeks) had no effect whereas both O2 and CO2 had a significant effect on L-AA retention. After 7 months of storage, no difference was found in dehydroascorbic acid concentration; the L-AA and total L-AA concentrations, in contrast, were significantly lower in the 5% CO2 conditions.  相似文献   

Corrigendum to “Automated observation and analysis of earthworm surface behaviour under experimental habitat quality and availability conditions” [Pedobiologia – International Journal of Soil Biology (53/4) 259–263]     

Jan Valckx  Annabel Pennings  Toon Leroy  Daniël Berckmans  Gerard Govers  Martin Hermy  Bart Muys 《Pedobiologia》2011,54(1):53-55

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Conservation agriculture as a sustainable option for the central Mexican highlands   总被引：1，自引：0，他引：1  

Bram Govaerts  Ken D. Sayre  Bart Goudeseune  Pieter De Corte  Kelly Lichter  Luc Dendooven  Jozef Deckers 《Soil & Tillage Research》2009,103(2):222

Tropical highlands of the world are densely populated and intensively cropped. Agricultural sustainability problems resulting from soil erosion and fertility decline have arisen all over this agro-ecological zone. Based on selected soil quality indicators, i.e. time-to-pond, aggregate distribution and stability (expressed as the mean weight diameter (MWD) for dry and wet sieving, respectively) and soil moisture, from a representative long-term sustainability trial initiated in 1991 in Central Mexico (2240 masl; 19.31°N, 98.50°W; Cumulic Phaeozem), some insights into the feasibility of conservation agriculture (CA) as part of a sustainable production system in the tropical highlands are given. Zero tillage plots with crop residue removal showed low aggregate distribution (average MWD = 1.34 mm) and stability (average MWD = 0.99 mm) resulting in top layer slaking, increased erosion and low time-to-pond values. Retaining the residue in the field with zero tillage avoided the above-mentioned negative evolution for both aggregate distribution as stability (average MWD = 2.77 and 1.51 mm, respectively) and even improved the physical conditions of the soil as compared to conventional practice. Throughout the growing season the lowest soil moisture content was found in zero tillage without residue (average over the entire growing season = 20.5% volumetric moisture content), the highest in zero tillage with residue retention (average = 29.7%) while conventional tillage had intermediate soil moisture values (average = 27.4%). Zero tillage without residue retention had most days of soil moisture values under permanent wilting point, while zero tillage with residue retention had the least. Taking into account these results, zero tillage with residue retention can clearly be a part of an integrated watershed management scheme towards sustainable agriculture in the tropical highlands. It is clear that to develop new management practices to improve water use, reduce erosion and enhance human labor/animal power focus must be on the use of conservation agriculture both for rainfed as well as irrigated production systems and be fine tuned for each system.  相似文献