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Berlin Brandenburg

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  • 1
    In: PLoS ONE, 2014, Vol.9(8)
    Description: Rhizosphere competence of bacterial inoculants is assumed to be important for successful biocontrol. Knowledge of factors influencing rhizosphere competence under field conditions is largely lacking. The present study is aimed to unravel the effects of soil types on the rhizosphere competence and biocontrol activity of the two inoculant strains Pseudomonas jessenii RU47 and Serratia plymuthica 3Re4-18 in field-grown lettuce in soils inoculated with Rhizoctonia solani AG1-IB or not. Two independent experiments were carried out in 2011 on an experimental plot system with three soil types sharing the same cropping history and weather conditions for more than 10 years. Rifampicin resistant mutants of the inoculants were used to evaluate their colonization in the rhizosphere of lettuce. The rhizosphere bacterial community structure was analyzed by denaturing gradient gel electrophoresis of 16S rRNA gene fragments amplified from total community DNA to get insights into the effects of the inoculants and R. solani on the indigenous rhizosphere bacterial communities. Both inoculants showed a good colonization ability of the rhizosphere of lettuce with more than 10 6 colony forming units per g root dry mass two weeks after planting. An effect of the soil type on rhizosphere competence was observed for 3Re4-18 but not for RU47. In both experiments a comparable rhizosphere competence was observed and in the presence of the inoculants disease symptoms were either significantly reduced, or at least a non-significant trend was shown. Disease severity was highest in diluvial sand followed by alluvial loam and loess loam suggesting that the soil types differed in their conduciveness for bottom rot disease. Compared to effect of the soil type of the rhizosphere bacterial communities, the effects of the pathogen and the inoculants were less pronounced. The soil types had a surprisingly low influence on rhizosphere competence and biocontrol activity while they significantly affected the bottom rot disease severity.
    Keywords: Research Article ; Biology And Life Sciences
    E-ISSN: 1932-6203
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  • 2
    Language: English
    In: Scientia Horticulturae, June 7, 2013, Vol.156, p.113(8)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scienta.2013.04.003 Byline: Martin Sandmann, Jan Graefe, Carmen Feller Abstract: acents Leaf area index is measured using direct and indirect methods with several setups. acents Direct methods are destructive, expensive, laborious and time-consuming. acents Less laborious indirect methods yielded precise values in kohlrabi and lettuce. acents Digital photography is a good alternative to destructive methods in these crops. Author Affiliation: Leibniz-Institute of Vegetable and Ornamental Crops Gro[sz]beeren and Erfurt, Theodor-Echtermeyer-Weg 1, 14979 Gro[sz]beeren, Germany Article History: Received 27 January 2012; Revised 18 February 2013; Accepted 2 April 2013
    Keywords: Digital Photography -- Methods
    ISSN: 0304-4238
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: PLoS ONE, August 6, 2014, Vol.9(8)
    Description: Rhizosphere competence of bacterial inoculants is assumed to be important for successful biocontrol. Knowledge of factors influencing rhizosphere competence under field conditions is largely lacking. The present study is aimed to unravel the effects of soil types on the rhizosphere competence and biocontrol activity of the two inoculant strains Pseudomonas jessenii RU47 and Serratia plymuthica 3Re4-18 in field-grown lettuce in soils inoculated with Rhizoctonia solani AG1-IB or not. Two independent experiments were carried out in 2011 on an experimental plot system with three soil types sharing the same cropping history and weather conditions for more than 10 years. Rifampicin resistant mutants of the inoculants were used to evaluate their colonization in the rhizosphere of lettuce. The rhizosphere bacterial community structure was analyzed by denaturing gradient gel electrophoresis of 16S rRNA gene fragments amplified from total community DNA to get insights into the effects of the inoculants and R. solani on the indigenous rhizosphere bacterial communities. Both inoculants showed a good colonization ability of the rhizosphere of lettuce with more than 10.sup.6 colony forming units per g root dry mass two weeks after planting. An effect of the soil type on rhizosphere competence was observed for 3Re4-18 but not for RU47. In both experiments a comparable rhizosphere competence was observed and in the presence of the inoculants disease symptoms were either significantly reduced, or at least a non-significant trend was shown. Disease severity was highest in diluvial sand followed by alluvial loam and loess loam suggesting that the soil types differed in their conduciveness for bottom rot disease. Compared to effect of the soil type of the rhizosphere bacterial communities, the effects of the pathogen and the inoculants were less pronounced. The soil types had a surprisingly low influence on rhizosphere competence and biocontrol activity while they significantly affected the bottom rot disease severity.
    Keywords: RNA ; Biological Pest Control
    ISSN: 1932-6203
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Agricultural and Forest Meteorology, 15 February 2015, Vol.201, pp.196-208
    Description: A model that predicts radiation transfer through single and double layers of plastic covering over kohlrabi canopies is developed, parameterised and tested. This model will be the foundation of an energy balance and growth module for covered kohlrabi crops that can be used in cover management. Radiation transfer through covers is based on their laboratory-measured angular-resolved transmittances, which are upscaled to non-plane covers in the field. The upscaling procedure accounts for distributed facet slopes according to the Beckmann distribution and visibility, as well as interception preference according to the cosine of the facet-ray incidence angle. Additional measured and upscaled quantities include absorptance and the degree of haze at several angles. The effects of plastic ageing and wetting are measured and implemented into the model using simple empirical approaches. Radiation transfer through the canopy is described by a thoroughly tested 1D canopy model, which accounts effectively for multiple reflections between leaves and the soil. A reanalysis of combined gap fraction and leaf area data from a previous study revealed a tendency of kohlrabi canopies to overdisperse at early growth stages, when only minor leaf area overlapping occurs. Using hourly measurements of photosynthetic active radiation flux densities at the soil level over two growth seasons at one site, the overall model performed reasonably well for a non-woven fabric-based cover ( = 1067, = 0.96, RMSE = 6.62 W m ) and a combination of a low-density polyethylene perforated plastic on top of a non-woven fabric ( = 1112, = 0.97, RMSE = 5.11 W m ). Simulations showed rather low degree of model sensitivity to the specification of cover roughness, but a high level of sensitivity to a proper parameterisation of angular optical properties of covers and of canopy radiation transfer in the NIR spectral range.
    Keywords: Plastic Covers ; Leaf Area Index ; Radiation Transfer ; Clumping Index ; Transmittance ; Soil Albedo ; Agriculture ; Meteorology & Climatology
    ISSN: 0168-1923
    E-ISSN: 1873-2240
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  • 5
    Language: English
    In: Agricultural and Forest Meteorology, Feb 15, 2015, Vol.201, p.196(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.agrformet.2014.10.011 Byline: Jan Graefe, Martin Sandmann Abstract: * A model to predict radiation transfer of plastic covered canopies is proposed. * Plastic transmittance, reflectance and haze are related to wetness, age and angle. * An upscaling procedure from plane to rough plastic surfaces is derived. * Kohlrabi canopies exhibit overdispersion at early vegetative stages. * Simulations are most sensitive to angular plastic properties and canopy processes. Author Affiliation: Leibniz-Institute of Vegetable and Ornamental Crops Gro[sz]beeren and Erfurt, Theodor-Echtermeyer-Weg 1, 14979 Gro[sz]beeren, Germany Article History: Received 6 May 2014; Revised 20 October 2014; Accepted 23 October 2014
    Keywords: Radiation (Physics) -- Optical Properties ; Radiation (Physics) -- Analysis
    ISSN: 0168-1923
    Source: Cengage Learning, Inc.
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  • 6
    Language: German
    In: Zeitschrift für das gesamte Kreditwesen : Pflichtblatt der Frankfurter Wertpapierbörse, 2011, Vol.64(3), pp. 145-147
    ISSN: 03414019
    Source: Deutsche Zentralbibliothek für Wirtschaftswissenschaften
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  • 7
    Language: English
    In: Plant disease, June 2018, Vol.102(6), pp.1101-1107
    Description: Fluorescence, normalized difference vegetation index, and thermal imaging are three frequently used nondestructive methods to detect biotic stress in plants. Due, in part, to the inconsistent results reported in the literature and the lack of measurements on the whole-plant scale, we tested the suitability of a wide variety of variables obtained using these three imaging methods to classify young plants into biotically stressed and nonstressed plants. To this end, we applied the model plant-pathogen system lettuce-Rhizoctonia solani. The relevant data from each image and plant (healthy and diseased) was extracted semiautomatically using sophisticated image processing algorithms. This method enabled us to identify the most appropriate variables via discriminant function and logistic regression analysis: photosystem II maximum quantum yield (F/F) and fluorescence decline ratio can be used to classify variables with an error ≤0.052. Lettuce seedlings with an F/F ratio 〉 0.73 were consistently healthy. In some cases, it was possible to detect infection prior to the appearance of symptoms. Possibilities to transfer the method to horticultural practice are discussed.
    Keywords: Fluorescence ; Plant Diseases ; Thermography ; Lettuce -- Physiology
    ISSN: 0191-2917
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  • 8
    Language: English
    In: Frontiers in Plant Science, 01 February 2018, Vol.9
    Description: Arbuscular mycorrhizal fungi (AMF) proliferate in soil pores, on the surface of soil particles and affect soil structure. Although modifications in substrate moisture retention depend on structure and could influence plant water extraction, mycorrhizal impacts on water retention and hydraulic...
    Keywords: Arbuscular Mycorrhiza ; Water Retention ; Drought ; Tomato ; Transpiration ; Soil Properties ; Botany
    E-ISSN: 1664-462X
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  • 9
    Language: English
    In: Scientia Horticulturae, 07 June 2013, Vol.156, pp.113-120
    Description: The dimensionless leaf area index (LAI) is a fundamental crop characteristic. Since the direct measurement of LAI or leaf area is labour intensive and destructive, fast and reliable indirect methods have been devised to estimate LAI of different crops. The objective of this work was to test indirect methods for the non-destructive estimation of LAI in kohlrabi ( L.) and lettuce ( L.). Focusing on the gap fraction methodology, digital photographs and simultaneous radiation interception measurements were taken using a Li-Cor plant canopy analyser (LAI-2200) on 12 sampling dates from planting to harvest, with concurrent destructive estimations of the leaf area. Several geometric protocols of the LAI-2200 and inversion algorithms of the accompanying software were evaluated. Very good indirect-direct LAI relationships were obtained for kohlrabi ( 〉 0.97, = 12) and lettuce ( 〉 0.99, = 9) for the most suitable protocols and algorithms.
    Keywords: Brassica Oleracea Var. Gongylodes L ; Lactuca Sativa Var. Capitata L ; Leaf Area Index ; Plant Canopy Analyser ; Gap Fraction ; Agriculture
    ISSN: 0304-4238
    E-ISSN: 1879-1018
    Source: ScienceDirect Journals (Elsevier)
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  • 10
    Language: English
    In: Frontiers in microbiology, 2014, Vol.5, pp.144
    Description: The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for 10 years under the same agricultural management to reveal differences directly linked to the soil type and not influenced by other factors such as climate or cropping history. Bulk soil and rhizosphere samples were collected 3 and 7 weeks after planting. The analysis of 16S rRNA gene fragments amplified from total community DNA by denaturing gradient gel electrophoresis and pyrosequencing revealed soil type dependent differences in the bacterial community structure of the bulk soils and the corresponding rhizospheres. The rhizosphere effect differed depending on the soil type and the plant growth developmental stage. Despite the soil type dependent differences in the bacterial community composition several genera such as Sphingomonas, Rhizobium, Pseudomonas, and Variovorax were significantly increased in the rhizosphere of lettuce grown in all three soils. The number of rhizosphere responders was highest 3 weeks after planting. Interestingly, in the soil with the highest numbers of responders the highest shoot dry weights were observed. Heatmap analysis revealed that many dominant operational taxonomic units were shared among rhizosphere samples of lettuce grown in diluvial sand, alluvial loam, and loess loam and that only a subset was increased in relative abundance in the rhizosphere compared to the corresponding bulk soil. The findings of the study provide insights into the effect of soil types on the rhizosphere microbiome of lettuce.
    Keywords: 16s Rrna Gene Analysis ; Dgge ; Lactuca Sativa ; Bacterial Communities ; Pyrosequencing ; Rhizosphere Responders
    ISSN: 1664-302X
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