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  • 1
    Electronic Resource
    Electronic Resource
    Do open-top chambers overestimate the effects of rising CO2 on plants? An analysis using spring wheat (1999)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 5 (1999), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The microclimate in facilities for studying effects of elevated CO2 on crops differs from ambient conditions. Open-top chambers (OTCs) increase temperature by 1–3 °C. If temperature and CO2 interact in their effect on crops, this would limit the value of OTC experiments. Furthermore, interaction of CO2 and temperature deserves study because increases in atmospheric CO2 concentration are expected to cause global warming.This paper describes two experiments in which a recently developed cooling system for OTCs was used to analyse the effects of temperature on photosynthesis, growth and yield of spring wheat (Triticum aestivum L., cv. Minaret). Two levels of CO2 were used (350 and 700 ppm), and two levels of temperature, with cooled OTCs being 1.6–2.4 °C colder than noncooled OTCs.Photosynthetic rates were increased by elevated CO2, but no effect of temperature was found. Cross-switching CO2 concentrations as well as determination of A–Ci curves showed that plant photosynthetic capacity after anthesis acclimated to elevated CO2. The acclimation may be related to the effects of CO2 on tissue composition: elevated CO2 decreased leaf nitrogen concentrations and increased sugar content. Calculations of the seasonal mean crop light-use efficiency (LUE) were consistent with the photosynthesis data in that CO2 increased LUE by 20% on average whereas temperature had no effect. Both elevating CO2 and cooling increased grain yield, by an average of 11% and 23%, respectively. CO2 and temperature stimulated yield via different mechanisms: CO2 increased photosynthetic rate, but decreased crop light interception capacity (LAI), whereas cooling increased grain yield by increasing LAI and extending the growing season with 10 days. The effects of CO2 and temperature were not additive: the CO2 effect was about doubled in the noncooled open-top chambers. In most cases, effects on yield were mediated through increased grain density rather than increased individual grain weights.The higher growth response to elevated CO2 in noncooled vs. cooled OTCs shows that a cooling system may remove a bias towards overestimating crop growth response to CO2 in open-top chambers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1999.00233.x
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  • 2
    Electronic Resource
    Electronic Resource
    Extension of a biochemical model for the generalized stoichiometry of electron transport limited C3 photosynthesis (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 27 (2004), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The widely used steady-state model of Farquhar et al. (Planta 149: 78–90, 1980) for C3 photosynthesis was developed on the basis of linear whole-chain (non-cyclic) electron transport. In this model, calculation of the RuBP-regeneration limited CO2-assimilation rate depends on whether it is insufficient ATP or NADPH that causes electron transport limitation. A new, generalized equation that allows co-limitation of NADPH and ATP on electron transport is presented herein. The model is based on the assumption that other thylakoid pathways (the Q-cycle, cyclic photophosphorylation, and pseudocyclic electron transport) interplay with the linear chain to co-contribute to a balanced production of NADPH and ATP as required by stromal metabolism. The original model assuming linear electron transport limited either by NADPH or by ATP, predicts quantum yields for CO2 uptake that represent the highest and the lowest values, respectively, of the range given by the new equation. The applicability of the new equation is illustrated for a number of C3 crop species, by curve fitting to gas exchange data in the literature. In comparison with the original model, the new model enables analysis of photosynthetic regulation via the electron transport pathways in response to environmental stresses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01224.x
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  • 3
    Electronic Resource
    Electronic Resource
    Photosynthesis is not impaired in healthy tissue of blighted potato plants (1990)
    Springer
    European journal of plant pathology 96 (1990), S. 55-63 
    Details
    ISSN: 1573-8469
    Keywords: late blight ; Phytophthora infestans ; dark respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Bepalingen van netto fotosynthesesnelheden, bij verschillende aardappelrassen, werden uitgevoerd in het veld en onder geconditioneerde omstandigheden. De metingen werden gedaan aan groen blad van planten die in verschillende mate waren aangetast doorPhytophthora infestans. Infectie had geen significante invloed op de netto fotosynthesesnelheid bij lichtverzadiging, de efficiëntie van lichtbenutting bij lage lichtintensiteit, of de donkerademhaling. Het effect vanP. infestans op de knolopbrengst van aardappelrassen lijkt uitsluitend veroorzaakt te zijn door een vermindering van groen bladoppervlak. Daarom is selectie van aardappelgenotypen met superieure handhaving van fotosynthetische activiteit bij aantasting, geen kansrijk veredelingsdoel.
    Notes: Abstract The net photosynthetic rates of green leaf tissue of potato plants of different cultivars were measured in the field and in a controlled environment after infection of the plants byPhytophthora infestans. Infection had no significant effect on the net photosynthetic rate at light saturation, the efficiency of light use at low light intensities, or dark respiration. The reported effect ofP. infestans on tuber yield seems to be caused solely by a reduction in the green leaf area. Therefore, a high rate of photosynthesis in green leaf tissue of infected plants is not a good selection criterion for potato genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02005129
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison of soil core sampling and minirhizotrons to quantify root development of field-grown potatoes (1996)
    Springer
    Plant and soil 182 (1996), S. 301-312 
    Details
    ISSN: 1573-5036
    Keywords: potato cyst nematodes (Globodera pallida) ; rooting depth ; soil compaction ; soil temperature ; spatial distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root growth of potato (Solanum tuberosum L.) is sensitive to soil conditions. A reduced root system size can result in reduced uptake of water and/or nutrients, leading to impaired crop growth. To understand the mechanisms by which soil conditions affect crop growth, study of temporal and spatial development of roots is required. In field experiments, effects of soil temperature, soil compaction and potato cyst nematodes (Globodera pallida) on root growth of potato cultivars were studied using two methods: core sampling and vertically oriented minirhizotrons. Minirhizotrons showed relatively more roots in deeper soil layers than core sampling, probably because of preferential root growth along the tube. Spatial distribution of roots should therefore be analysed by core sampling. To eliminate differences in spatial distribution, total root systems as measured by both methods were compared. Nematodes, cultivars and time did not affect the relationship between both methods. Soil compaction, however, affected it because of a strong response of root length in bulk soil and small differences in root number against the minirhizotron, suggesting that soil coring has to be used to study effects of different bulk densities. With both methods, sequential measurements of roots give the net effect of root growth and decay. Data on root turnover can only be obtained with minirhizotrons by comparing video recordings of different dates. Other information obtained with minirhizotrons is the average orientation of roots. Moreover, the minirhizotron method has the advantage of demanding less labour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029061
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  • 5
    Electronic Resource
    Electronic Resource
    Selection and use of a mathematical model to evaluate components of resistance to Phytophthora infestans in potato (1992)
    Springer
    European journal of plant pathology 98 (1992), S. 192-202 
    Details
    ISSN: 1573-8469
    Keywords: late blight ; epidemiology ; resistance breeding ; genetic variation ; sensitivity analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Five models of general epidemics, spatially homogeneous, were all shown to fit well to disease progress data forPhytophthora infestans on a susceptible potato cultivar. The models were: the logistic equation, the paralogistic or Vanderplank equation, two models from medical epidemiology with similar complexity, and a slightly more complex model with explicit treatment of lesion expansion. The use of the models for analysing the sensitivity of disease progress to changes in resistance components is discussed. Sensitivity analysis of the most complex model, by varying components within their range of genetic variation, indicates lesion expansion and infection efficiency as the components offering the best perspectives for resistance breeding. Improving two components simultaneously reduces disease progress slightly more than additively, but not enough to add other components to the list of breeding objectives. Pitfalls in using models for component sensitivity analysis, in the form of erroneous model initializations, are discussed, including implications for the role of components in the development of natural epidemics and in resistance breeding trials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974382
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  • 6
    Electronic Resource
    Electronic Resource
    Scenario studies for future agriculture and crop protection (1997)
    Springer
    European journal of plant pathology 103 (1997), S. 197-201 
    Details
    ISSN: 1573-8469
    Keywords: decision making ; methodology ; production ecology ; technology evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The history of crop protection has shown two shifts of focus. In the second half of this century, attention shifted from the pathogen to the pathosystem, and at present we are witnessing a further shift to a focus on the whole production system. So, crop protection is now seen as just one activity among many in agricultural production systems and improvement of crop protection is no longer seen as separate from goals such as maximizing yield and minimizing inputs, as for example nitrate use per unit of product and use of pesticides per unit of land. To explore options for future crop protection in conjunction with other production goals, scenario studies can be useful tools. Scenario studies may be used for the evaluation of technologies or may comprise feasibility analyses of land use at various aggregation levels. The methodology of scenario studies is explained in this paper and some examples are described. It is demonstrated how useful organised thinking about the future can be.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008618109374
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  • 7
    Electronic Resource
    Electronic Resource
    Evaluation of breeding strategies for resistance and tolerance to late blight in potato by means of simulation (1992)
    Springer
    European journal of plant pathology 98 (1992), S. 3-11 
    Details
    ISSN: 1573-8469
    Keywords: Phytophthora infestans ; accelerated senescence ; light interception ; yield ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment with three potato cultivars, where plants were inoculated withPhytophthora infestans, was used to parameterize a model of potato growth and blight population dynamics. The model was validated by accurately simulating a field experiment conducted in another year. Sensitivity analysis with the model showed that late cultivars are longer able to maintain a green canopy in the presence of disease, but still suffer more yield loss than early cultivars. The level of partial resistance of a cultivar was more important than its level of tolerance, and other plant characteristics. The model calculations showed that only between 4 and 15% of the yield loss in the experiments was due to accelerated leaf senescence caused by the disease; the major part of the loss was caused by lesion coverage of leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01998073
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  • 8
    Electronic Resource
    Electronic Resource
    Light use efficiencies of potato cultivars with late blight (Phytophthora infestans) (1991)
    Springer
    Potato research 34 (1991), S. 123-132 
    Details
    ISSN: 1871-4528
    Keywords: ground cover ; light interception ; tuber yield ; Solanum tuberosum L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato cultivars of different maturity classes and levels of resistance toPhytophthora infestans were grown under several disease intensities in three field trials. Seasonal courses of ground cover by green foliage and final tuber yields were determined. Light use efficiencies (LUE) were calculated from regression analyses of yield on cumulative light interception. Late blight reduced tuber yields by decreasing cumulative light interception without affecting LUE. No differences in LUE between cultivars or cultivar classes were detected. Therefore, the maintenance of green leaf area is important when breeding potatoes for optimal performance in the presence of late blight. The results support the hypothesis that the correlation between lateness and reported resistance of potato cultivars is due to the vigorous foliage growth of late cultivars.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358033
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  • 9
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    Inhibition of Tat-mediated transactivation and HIV replication with Tat mutant and repressor domain fusion proteins (1998)
    Springer Nature
    Details
    Publication Date: 1998-07-01
    Print ISSN: 0969-7128
    Electronic ISSN: 1476-5462
    Topics: Biology , Medicine
    Published by Springer Nature
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  • 10
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    Nodding Syndrome in Onchocerciasis Endemic Areas (2016)
    Cell Press
    Details
    Publication Date: 2016-08-01
    Print ISSN: 1471-4922
    Electronic ISSN: 1471-5007
    Topics: Biology , Medicine
    Published by Cell Press
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