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  • 1
    Electronic Resource
    Electronic Resource
    Stomatal control of xylem embolism (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The potential role of stomatal closure in the control of xylem embolism is investigated by means of a simple model of hydraulic flow in plants. Maintenance of a maximally efficient conducting system requires the stomata to close in an appropriate fashion as evaporative demand increases in order to prevent shoot water potentials falling below the threshold value at which cavitations occur. The model showed that the optimal stomatal behaviour required depends on soil water availability. Further analysis of the model demonstrated that there could be certain circumstances where loss of a proportion of the conducting tissue by embolisms can, perhaps surprisingly, be beneficial in terms of maximizing stomatal aperture and hence short-term productivity. The results are discussed in relation to the signals controlling stomatal aperture, and it is shown that (1) optimal control cannot be obtained using information on leaf water potential alone, and (2) information relating to soil water potential is a necessary requirement for optimal control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb01532.x
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of Selected Element Concentrations and Enrichment Ratiosin Background and Anthropogenically Impacted Roadside Areas (2000)
    Springer
    Archives of environmental contamination and toxicology 38 (2000), S. 428-438 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Previous research by the National Contaminant Biomonitoring Program found fish from Manoa Stream, Hawaii, to have the highest concentrations of Pb in the nation. To explore possible source linkages we sampled background (uncontaminated) soil, roadside soil, and road deposited sediment in Manoa watershed and analyzed them for total and extractable concentrations of Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn. Our concentration and enrichment ratio data indicate that Al, Co, Fe, Mn, and Ni were controlled by natural source variations, and Cu, Zn, and particularly Pb were anthropogenically enhanced. Labile Pb concentrations, extracted with either dilute HCl or EDTA, reached a maximum of 3,560 mg/kg compared to background values of 〈10 mg/kg. Additionally, 25% of the 169 contaminated samples analyzed had EDTA-extractable Pb enrichment ratios ≥11.5, where a value of 1 separates uncontaminated from contaminated media. Given the proximity of most samples to roadways it is reasonable to conclude that automotive emissions plus vehicle wear were the primary contributors of trace metals to the roadside system. These data are discussed in context with previous work on the fluvial bed sediments in this watershed in an attempt to examine the potential linkage with the biological accumulation of Pb in fish from Manoa watershed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002440010057
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  • 3
    Electronic Resource
    Electronic Resource
    Bed sediment-associated trace metals in an urban stream, Oahu, Hawaii (2000)
    Springer
    Environmental geology 39 (2000), S. 611-627 
    Details
    ISSN: 1432-0495
    Keywords: Key words Lead ; Bed sediments ; Enrichment ratios ; Modified index of geoaccumulation ; Manoa Stream ; Trace metals ; Spatial variation ; Phase associations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Of the 117 stream and lake systems sampled nationwide, fish from Manoa Stream on Oahu, Hawaii, have consistently shown the highest Pb concentrations. Therefore a detailed study was conducted to examine total metal contents in bed sediments from a 5.8-km stretch of Manoa Stream. A total of 123 samples (〈63 μm) were examined for 18 elements and 14 samples for 21 elements. Selected samples were also examined using different leach solutions to examine metal phase associations. All trace metal data, computations of enrichment ratios and the modified index of geoaccumulation point to mineralogical control for Cr and Ni; minor anthropogenic contamination for Ba, Cd, Cu, Hg and Zn; and a very strong contamination signal for Pb. Maximum Pb contents (up to 1080 mg kg−1) were associated with anthropogenic material dumping in minor tributaries, storm sewer sediments and sediments in the “lower” section of the basin. Proportionally Pb had the highest non-residual component of elements examined; dominantly in the reducible phase associated with Mn and amorphous Fe oxyhydroxides. The contamination signal was typically lowest in the “undisturbed” headwater reach of the basin (above 5.1 km) with significant increases throughout the “residential” and “commercial-institutional” zones of the mid-basin. The spatial pattern of bed sediment contamination and evidence from storm sewer-outlet sediments strongly indicates that Pb, and to a lesser degree some other metals, is still being transported to the stream and the primary agent is soil erosion and transport of metals sorbed to sediments. The primary source of sediment-associated metals is considered to be the automobile, though other minor sources can not be ruled out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002540050473
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  • 4
    Electronic Resource
    Electronic Resource
    Observations of the convective plume of a lake under cold-air advective conditions (1978)
    Springer
    Boundary layer meteorology 14 (1978), S. 543-556 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Moderating effects of Lake Apopka, Florida on downwind surface temperatures were evaluated under cold-air advective conditions. Point temperature measurements north and south of the lake and data obtained from a thermal scanner flown at 1.6 km indicate that surface temperatures directly downwind may be higher than surrounding surface temperatures by as much as 5 °C under conditions of moderate winds (~4 m s−1). No substantial temperature effects were observed with surface wind speed less than 1 m s−1. Fluxes of sensible and latent heat from Lake Apopka were calculated from measurements of lake temperature, net radiation, relative humidity and air temperature above the lake. Bulk transfer coefficients and the Bowen ratio were calculated and found to be in agreement with reported data for non-advective conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121893
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  • 5
    Electronic Resource
    Electronic Resource
    Simulating the moderating effect of a lake on downwind temperatures (1979)
    Springer
    Boundary layer meteorology 16 (1979), S. 23-33 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A steady-state, two-dimensional numerical model is used to simulate air temperatures and humidity downwind of a lake at night. Thermal effects of the lake were modelled for the case of moderate and low surface winds under the cold-air advective conditions that occur following the passage of a cold front. Surface temperatures were found to be in good agreement with observations. A comparison of model results with thermal imagery indicated the model successfully predicts the downwind distance for which thermal effects due to the lake are significant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02220404
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  • 6
    Electronic Resource
    Electronic Resource
    Response of winter wheat to N-fertiliser: Dynamic model (1987)
    Springer
    Nutrient cycling in agroecosystems 12 (1987), S. 139-156 
    Details
    ISSN: 1573-0867
    Keywords: grain dry weight ; grain %N ; nitrogen-fertiliser ; simulation model ; winter wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A concise computer simulation model is described for calculating the growth and N-content of winter-wheat. The validity of the model was tested by means of a new application of statistical theory against the results of nationwide fertiliser experiments having different designs. There was agreement within the limits of experimental error between the measured and simulated values of both total plant and of grain dry weight over the entire range of N-fertiliser treatments in the different experiments. The model also gave good estimates of the %N in the grain provided N-fertilizer levels were not high. Response curves, calculated from the model for grain yield, grain %N, are given for different combinations of potential yield, mineralisation rate and the distribution of inorganic-N down the soil profile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048914
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of gibberellic acid, fluridone, abscisic acid and paclobutrazol on anther culture of Brussels sprouts (1992)
    Springer
    Plant growth regulation 11 (1992), S. 81-84 
    Details
    ISSN: 1573-5087
    Keywords: anther culture ; gibberellic acid ; abscisic acid ; paclobutrazol ; fluridone ; Brassica oleracea ; Brussels sprouts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Both gibberellic acid (GA3) and fluridone, a non-specific inhibitor of ABA biosynthesis, promoted embryo production in anther cultures of Brussels sprouts cv. Hal, but not in cv. Gower. Abscisic acid (ABA) and the gibberellin-biosynthesis inhibitor paclobutrazol inhibited embryo production in both cultivars.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024438
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  • 8
    Electronic Resource
    Electronic Resource
    A mathematical description of a pump/leak/buffer model for plant nitrate uptake (1989)
    Springer
    Plant and soil 117 (1989), S. 299-300 
    Details
    ISSN: 1573-5036
    Keywords: differential equation ; diurnal ; nitrogen assimilation ; phase shift ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A pump/leak/buffer model of nitrate in plants is presented in the form of a differential equation, based on the computer simulation model of Scaife (1989). The equation is solved, and the long-term behaviour of the rate of nitrate uptake of the plants described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02220726
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  • 9
    Electronic Resource
    Electronic Resource
    The exploitation of genetic resources of Brassica oleracea in breeding for resistance to clubroot (Plasmodiophora brassicae) (1989)
    Springer
    Euphytica 42 (1989), S. 215-226 
    Details
    ISSN: 1573-5060
    Keywords: Brassica oleracea ; Plasmodiophora brassicae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary About 1000 Brassica oleracea accessions were evaluated in glasshouse tests for response to Plasmodiophora brassicae (clubroot). Resistance was confirmed in some north and west European kales and cabbage. A new source of resistance in cabbage, from Eire, is reported. Most other accessions were highly susceptible but lower levels of susceptibility were observed in open pollinated Brussels sprouts and forms of south European cabbage, cauliflower and broccoli. Modern breeding (as in the production of hybrid cultivars) appears to have resulted in increased susceptibility in several crop types. The implications of these results for the exploitation of germplasm are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034457
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  • 10
    Electronic Resource
    Electronic Resource
    The use of polyacrylamide gradient gel electrophoresis to identify variation in isozymes as markers for Lactuca species and resistance to the lettuce root aphid Pemphigus bursarius (1991)
    Springer
    Euphytica 56 (1991), S. 237-242 
    Details
    ISSN: 1573-5060
    Keywords: electrophoresis ; isozymes ; Lactuca spp. ; Iettuce root aphid Pemphigus bursarius
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This paper describes simple, routine polyacrylamide gradient gel electrophoresis of allozyme patterns surveyed in wild populations of four Lactuca species, obtained from the Wellesbourne Vegetable Gene Bank. Using multivariate statistical techniques, four allozyme bands were identified, which distinguished the four species, and an additional two bands, which were related to the resistance of Lactuca species to the lettuce root aphid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042370
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