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  • 1
    Electronic Resource
    Electronic Resource
    Carbon balance and water use efficiency of frequently cut Lolium perenne L. swards at elevated carbon dioxide (1997)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 3 (1997), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The impact of doubled atmospheric [CO2] on the carbon balance of regularly cut Lolium perenne L. swards was studied for two years under semi-field conditions in the Wageningen Rhizolab. CO2 and H2O vapour exchange rates of the swards were measured continuously for two years in transparent enclosures. The light utilization efficiencies of the swards ranged between 1.5 g CO2 MJ–1 global radiation (high light, ambient [CO2]) and 2.8 g CO2 MJ–1 (low light, doubled [CO2]). The above-ground net primary productivity (NPP) in the enclosures was greater by 29% in 1994 and 43% in 1995 in the doubled [CO2] treatments, but only 20% and 25% more carbon was recovered in the periodical cuts. Thus, NPP increased significantly more than did the harvested above-ground biomass. The positive [CO2] effect on net carbon assimilation is therefore associated with a preferential allocation of extra carbon to the roots and soil.In addition to higher canopy photosynthesis and leaf elongation rates, a small part of the positive [CO2] effects on NPP could be attributed to a decrease of the specific respiration of the shoots. On a canopy basis however, respiration was equal or slightly higher at doubled [CO2] due to the higher amount of standing biomass.Comparison of NPP and carbon recovered in different harvests showed that allocation to roots and soil was highest in spring, it was low in early summer and increased again in late summer and autumn.The total gross amount of carbon partitioned to the roots and soil during the two year period was 57% more at doubled [CO2]. The total amount of carbon that was sequestered in the soil after subtraction of the respiratory losses was 458 g m–2 and 779 g m–2 in the ambient and doubled [CO2] treatments, respectively.The average water use efficiency (WUE) of the swards was increased by a factor 1.5 at doubled [CO2]. Both WUE and its positive interaction with [CO2] varied between years and were positively correlated with global irradiance. At doubled [CO2], the higher WUE was fully compensated for by a higher leaf area index. Therefore, total transpiration on a canopy basis was equal for the ambient and the doubled [CO2] concentrations in both years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1997.00099.x
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  • 2
    Electronic Resource
    Electronic Resource
    The influence of cyst nematodes and drought on potato growth (1994)
    Springer
    European journal of plant pathology 100 (1994), S. 381-394 
    Details
    ISSN: 1573-8469
    Keywords: Globodera pallida ; Solanum tubersosum L. ; minirhizotron ; nitrogen depletion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In two experiments in the Wageningen Rhizolab with potato cv. Mentor planted in soils with or without potato cyst nematodes (Globodera pallida, W) the number of roots per cm2 was observed two weekly by video camera, in horizontally placed minirhizotrons at depths varying from 5 to 100 cm. In both experiments initial root growth was more rapid in the top soil of the uninfected soil. In the first experiment under optimal water supply, root formation continued longer in the top 30 cm of infested soil leading to twice as many roots at the end of the growing season as in uninfested soil. In the subsoil from 30 to 100 cm, however, root formation was strongly reduced by cyst nematodes leading to an uneven distribution of roots throughout the profile. In the second experiment potato cyst nematodes only increased rooting in the top soil with reduced irrigation. Potato cyst nematodes did not affect the water use efficiency of the crop whereas reduced irrigation increased water use efficiency by about 22%. Without potato cyst nematodes the soil profile was depleted of mineral nitrogen until a depth of 1 m whereas with high initial population densities no nitrogen was taken up in the subsoil between 30 and 100 cm. The spational heterogenity of roots and nitrogen in the soil is an important mechanism of damage. This finding may lead to improved cultural practices and breeding for tolerance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01874806
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  • 3
    Electronic Resource
    Electronic Resource
    Root growth of potato crops on a marine-clay soil (1986)
    Springer
    Plant and soil 94 (1986), S. 17-33 
    Details
    ISSN: 1573-5036
    Keywords: Auger ; Clay ; Potato ; Root ; Root density ; Root diameter ; Root dry weight ; Root length ; Root mass ; Root washing ; Soil core
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In 1982 and 1983 root samples were taken by auger from potato crops grown on marine clay in the Flevo-Polder. The roots increased their penetration depth throughout the periods of measurement, and ultimately reached depths between 80 cm and 100 cm below the hills. Between 50 and 60 days after emergence, decay of roots commenced, starting in the upper horizons. In the hill mean root length densities varied between 1 and 2 cm cm−3. Below the hills root density rarely exceeded 1 cm cm−3. The random variation in root density was equivalent to a coefficient of variation of 50%. There were significant effects of the position of sampling (relative to the centre of the plant) on root density; densities were usually lowest beneath the furrow. Depending on season and sampling date, total root length varied between 3.4 and 7.1 km m−2, and root dry mass varied between 33 and 77 g m−2. Representative figures for specific root length were 100–120 m g−1 dry weight. About 90% of the root diameters were smaller than 0.44 mm; the most frequent class (35%) were roots with diameters between 0.12 and 0.20 mm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02380587
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  • 4
    Electronic Resource
    Electronic Resource
    The Wageningen Rhizolab — a facility to study soil-root-shoot-atmosphere interactions in crops (1994)
    Springer
    Plant and soil 161 (1994), S. 289-298 
    Details
    ISSN: 1573-5036
    Keywords: anisotropy ; Brussels sprouts (Brassica oleracea L. var. gemmifera) ; leek (Allium porrum L.) ; minirhizotrons ; potatoes (Solanum tuberosum L.) ; rhizotron ; root length density ; rooting depth ; wheat (Triticum aestivum L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots in the Wageningen Rhizolab are observed using two methods: (i) non-destructively, using horizontal, glass minirhizotrons at intervals of 14 days between observations; (ii) with destructive sampling using augers on three dates in the season. This paper reports changes with depth and time in root numbers per unit interface area of the minirhizotron tube (number of intersections) of four crop species (wheat, Brussels sprouts, leek and potato). The number of root intersections of Brussels sprouts, wheat and potato declined with depth at any time, whereas leek showed a different pattern because maximum root growth was observed at a depth of 10–20 cm. Root density generally decreased in the following order: Brussels sprouts, wheat, potato and leek. Plots of root length densities, Lrv(cm. cm-3), obtained by auger sampling, versus the number of intersections showed considerable variation in slope with species, time in the season and year, implying that a single, universal equation to convert minirhizotron observations into volumetric root densities does not exist. Causes of variation in the slopes are discussed. It is concluded that limited auger sampling combined with minirhizotron observations yield adequate quantitative estimates of relevant root properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046400
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  • 5
    Electronic Resource
    Electronic Resource
    The Wageningen Rhizolab — a facility to study soil-root-shoot-atmosphere interactions in crops (1994)
    Springer
    Plant and soil 161 (1994), S. 275-287 
    Details
    ISSN: 1573-5036
    Keywords: crop growth ; gas exchange ; minirhizotrons ; nutrients ; photosynthesis ; respiration ; rhizotron ; root observation ; root growth ; water balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A research facility is described for the integrated study of soil-root-shoot-atmosphere relationships in crops. The Wageningen Rhizolab has been in use since 1990, and consists of two rows, each with eight below-ground compartments aligned along a corridor. A rain shelter automatically covers the experimental area at the start of rainfall. Compartments are 125 cm × 125 cm and 200 cm deep. Each compartment has a separate drip irrigation system. Crop canopy photosynthesis, respiration, and transpiration can be measured simultaneously and continuously on four out of eight compartments at a time. Each compartment can be filled with a selected soil material (repacked soil) and is accessible from the corridor over its full depth. Multiple sensors for measuring soil moisture status, electrical conductivity, temperature, soil respiration, trace gases and oxygen are installed in spatial patterns in accordance with the requirements of the experiments. Sensors are connected to control and data-acquisition devices. Likewise, provisions have been made to sample manually the soil solution and soil atmosphere. Root observation tubes (minirhizotrons) are installed horizontally at depth intervals ranging from 5 cm (upper soil layers) to 25 cm (below 1 m). The facility is at present in use to study growth and development of vegetation (crops) in relation to drought, nutrient status, soil-borne diseases, and underground root competition. One important application is the study of elevated CO2 concentration and climate change and the way they affect crops and their carbon economy. Growth and development of field grown vegetables and winter cover crops are also evaluated. The common aspect of those studies is to gain a better understanding of crop growth under varying environmental conditions, and to collect datasets that may help to improve mechanistic crop growth simulation models that can address suboptimal growth conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046399
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  • 6
    Electronic Resource
    Electronic Resource
    Estimation of root densities by observation tubes and endoscope (1983)
    Springer
    Plant and soil 74 (1983), S. 295-300 
    Details
    ISSN: 1573-5036
    Keywords: Endoscope ; Potatoes ; Root density ; Root length ; Soil core ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary It was determined experimentally whether the amount of roots, viewed by endoscope in observation tubes (cm cm−2) is related to root density (cm cm−3) in adjacent bulk soil, determined by core sampling. For wheat plants the results can be summarized by the equation: root length (cm cm−2, endoscope)=0.29 times root density (cm cm−3, soil cores). Results for potato plants could not be interpreted as unequivocally as for wheat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02143621
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  • 7
    Electronic Resource
    Electronic Resource
    Automated measurement of root length with a three-dimensional high-resolution scanner and image analysis (1994)
    Springer
    Plant and soil 158 (1994), S. 145-149 
    Details
    ISSN: 1573-5036
    Keywords: image analysis ; Line-Intersect Method ; root length ; three-dimensional scanner
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract For measuring the length of root samples, the use of a three-dimensional (3D) scanner is proposed to address the problem of a too low resolution. The scanner's high resolution (up to 354 pixels per cm) enables in the resulting grey-value image very thin roots (diameter 100 μm) to be segmented from the background by a simple thresholding operation. After skeletonizing, total length of the roots is calculated by multiplying the number of skeleton pixels by a correction factor. A comparison with the modified Newman Line-Intersect Method showed a correlation of r=0.98. Besides its superior resolution, an advantage of this type of scanner is its focusing depth, which allows root samples to be recorded on the scanbed similarly to a camera-oriented system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007928
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic differences in water-use efficiency, stomatal conductance and carbon isotope fractionation in potato (1989)
    Springer
    Potato research 32 (1989), S. 113-121 
    Details
    ISSN: 1871-4528
    Keywords: carbon isotope discrimination ; drought ; stomatal frequency ; stomatal resistance ; transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato (Solanum tuberosum L.) cultivars were grown in pots and containers under a rain shelter to examine differences in stomatal conductance, water-use efficiency, and carbon isotope fractionation. Conductance was measured on abaxial leaf surfaces with a steady state diffusion porometer. Carbon isotopic analyses were made with an isotope ratio mass spectrometer. Water-use efficiency (WUE) was obtained by dividing total dry matter production by cumulative transpiration. Significant genetic variation was observed for each trait. WUE was positively related to carbon isotope fractionation (13∈) and was inversely related to stomatal conductance. Carbon isotope analysis and porometry show potential as indirect screening methods to identify genetic differences in water-use efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358219
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  • 9
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    Estimation of root densities by observation tubes and endoscope (1983)
    Springer
    Details
    Publication Date: 1983-06-01
    Print ISSN: 0032-079X
    Electronic ISSN: 1573-5036
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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  • 10
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    The Wageningen Rhizolab — a facility to study soil-root-shoot-atmosphere interactions in crops (1994)
    Springer
    Details
    Publication Date: 1994-04-01
    Print ISSN: 0032-079X
    Electronic ISSN: 1573-5036
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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