ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • maize  (5)
  • thin-section technique  (3)
  • root distribution  (2)
Collection
Keywords
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    WaNuLCAS, a model of water, nutrient and light capture in agroforestry systems (1998)
    Springer
    Agroforestry systems 43 (1998), S. 217-242 
    Details
    ISSN: 1572-9680
    Keywords: competition ; resource capture ; root distribution ; simulation ; stella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Models of tree-soil-crop interactions in agroforestry should maintain a balance between dynamic processes and spatial patterns of interactions for common resources. We give an outline and discuss major assumptions underlying the WaNuLCAS model of water, nitrogen and light interactions in agroforestry systems. The model was developed to deal with a wide range of agroforestry systems: hedgerow intercropping on flat or sloping land, fallow-crop mosaics or isolated trees in parklands, with minimum parameter adjustments. Examples are presented for simulation runs of hedgerow intercropping systems at different hedgerow spacings and pruning regimes, a test of the safety-net function of deep tree roots, lateral interactions in crop-fallow mosaics and a first exploration for parkland systems with a circular geometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026417120254
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Root-soil contact of maize, as measured by a thin-section technique (1992)
    Springer
    Plant and soil 139 (1992), S. 119-129 
    Details
    ISSN: 1573-5036
    Keywords: image analysis ; maize ; nearest-neighbour distance ; root-soil contact ; soil compaction ; soil porosity ; thin-section technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The degree of root-soil contact was evaluated from thin sections for maize grown in pots with soil aggregates packed at three bulk densities. Root-soil contact was found to increase with bulk density of the soil. For soils with a porosity of 60, 51 and 44% (v/v), the average fraction of root-soil contact was 60, 72 and 87%, respectively. The frequency distribution of nearest-neighbour distances from points in a void to the nearest point of the soil matrix was measured. This was then used for a statistical test of a null hypothesis of random positioning of roots in voids. Where roots grew in larger pores or voids the degree of root-soil contact was greater than expected for random positioning of roots. Possible mechanisms of the observed preference of roots for proximity to the soil, and higher root-soil contact are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012849
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Root-soil contact of maize, as measured by a thin-section technique (1992)
    Springer
    Plant and soil 139 (1992), S. 109-118 
    Details
    ISSN: 1573-5036
    Keywords: freeze-drying ; maize ; root-soil contact ; soil compaction ; soil porosity ; thin-section technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In models of oxygen, water and nutrient uptake by plant roots, the degree of root-soil contact is an important parameter. An observation technique is required to evaluate to what extent root-soil contact depends on plant species, soil texture and structure. Thin sections for studying soil structure may be used for this purpose, provided that roots do not shrink during section preparation, and that all root cross sections are recognized. Maize was grown in pots with soil aggregates obtained by sieving and compacting to three bulk densities. Thin sections were made by freeze-drying samples before impregnating the soil with resin. Two checks were made on the validity of the method. Firstly, visual appearance of roots with intact epidermis, cortex and other tissues did not show signs of shrinkage. Secondly, the agreement was checked between root lengths obtained by washing duplicate soil samples and the number of root cross sections counted on horizonal and vertical thin sections. For the latter, the angle at which roots intersected the thin-section plane was determined from the shape of the cross sections. The frequency distribution of calculated angles was in agreement with the frequency distribution expected for a randomly oriented set of cylinders when an error term was included in the simulated measurements. Some results are presented for a field test of the thin-section method with barley on a calcareous marine sandy loam. Root hairs, apparently undamaged by sample preparation, are important for bridging the gap between roots and soil in this situation. According to the experience presented, the thin-section technique is suitable to derive the degree of root-soil contact, as influenced by species, soil texture and structure, in samples obtained from pot or field experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012848
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Root-soil contact of maize, as measured by a thin-section technique (1992)
    Springer
    Plant and soil 139 (1992), S. 131-138 
    Details
    ISSN: 1573-5036
    Keywords: maize ; nitrate uptake ; root-soil contact ; soil compaction ; soil porosity ; thin-section technique ; water uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Whilst adverse effects of soil compaction on plant growth are well known, experimental evidence also suggests that a very loose soil can adversely affect crop growth. We tested the hypothesis that poor root-soil contact in a loose soil is partly responsible for the existence of an optimum in the response curve of crops to soil compaction. In a pot experiment with maize at restricted nitrogen supply, five levels of soil compaction were compared and the percentage root-soil contact was measured in three of these. At the highest soil porosity tested, shoot growth was slightly slower than that at intermediate soil porosity. In the more compacted soil, shoot growth clearly lagged behind. Shoot fresh weight per unit root length decreased with increasing soil porosity over the whole range tested. In the most compacted soil, roots were mainly restricted to the upper zones of the pot and total root length was smaller than in less compacted soil. Water and nitrate uptake were highest at the intermediate pore volume and slightly lower at the highest soil porosity. Water absorption and nitrate uptake per unit root length decreased from compacted to loose soil with decreasing root-soil contact. This effect was more than proportional with the percentage root-soil contact and was in line with a correction value based on a transport model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012850
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Gas-filled root porosity in response to temporary low oxygen supply in different growth stages (1993)
    Springer
    Plant and soil 152 (1993), S. 187-199 
    Details
    ISSN: 1573-5036
    Keywords: aeration ; aerenchyma ; carnation ; cucumber ; gerbera ; maize ; oxygen stress ; oxygen transport ; redox dye ; rice ; rose ; sugar beet ; sweet pepper ; tomato ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development of gas-filled root porosity in response to temporary low oxygen supply was tested for a range of edible and ornamental crops: rice, maize, wheat, sugar beet, tomato, cucumber, sweet pepper, carnation, gerbera and rose. In a first experiment, the roots of tomato, maize and gerbera had a higher gas-filled root porosity, Ep (% v/v), when grown permanently in a non-aerated instead of aerated solution. The Ep of roots increased during two weeks when half the root system of a young plant was transferred to a non-aerated solution; in older plants this response was not seen. Carnation had a negligible gas-filled porosity in all treatments. In a second experiment, a comparison was made between high (20 kPa) and low (about 2 kPa) O2 partial pressure in a recirculating nutrient solution. Half of the root system was transferred to low O2 at various growth stages. In most species older plants did not increase Ep on exposure to low O2. For tomato, sweet pepper and rose, Ep was normally in the range 3–8% (v/v). Young plants of cucumber, wheat and sugar beet also had an Ep in that range, but in older plants values ranged from 1 to 3%. Transverse root sections examined by light microscopy showed, on average, 60% more intercellular spaces in the root cortex than the measurements of gas-filled porosity, probably because some gaps and spaces in the cortex were not gas-filled. This effect was most pronounced in tomato. A negative pressure in the cortex may be needed for gaps to be gas-filled. An exodermis may increase the effectiveness of gas spaces in the cortex by closing the gas channels and, by offering some resistance to water uptake, allowing a negative pressure head in the cortex which keeps gaps gas-filled. A redox dye method was developed to study the length of root which is effectively supplied with oxygen, as a function of Ep. Results indicated that for every percent Ep the root can remain aerated over at least 1 cm in a non-aerated medium under the conditions of the test.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029088
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Heavy-metal uptake by crops from polluted river sediments covered by non-polluted topsoil (1995)
    Springer
    Plant and soil 175 (1995), S. 105-113 
    Details
    ISSN: 1573-5036
    Keywords: cadmium ; root distribution ; root methods ; soil pollution ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cadmium uptake by maize from polluted river sediments covered with a clean top layer of variable thickness is discussed in relation to root distribution. Two pathways for uptake are distinguished: roots penetrating the contaminated layer or contaminants moving into the root zone. Relative Cd uptake proved to be roughly proportional to the fraction of total root length found in the contaminated layer. A deeper water table induced a deeper root development and more Cd uptake for a given thickness of clean topsoil. A model based on exponential decrease of root length density with depth is acceptable as first approximation only. Little or no evidence was found for contaminants moving into the root zone during the ten years of the experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02413015
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Old tree root channels in acid soils in the humid tropics: Important for crop root penetration, water infiltration and nitrogen management (1991)
    Springer
    Plant and soil 134 (1991), S. 37-44 
    Details
    ISSN: 1573-5036
    Keywords: cassava ; Guelph permeameter ; leaching ; maize ; methylene blue ; rice ; rooting depth ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under high rainfall conditions on acid soils with shallow crop root systems the rate of N leaching is high. A simple model predicts nitrogen uptake efficiency as a function of the amount of rainfall in excess of evapotranspiration, rooting depth and degree to which N leaching is retarded in comparison with water transport. Field observations on acid soils in S.E. Nigeria and S. Sumatera (Indonesia) showed that this model should be amended to include the role of old tree root channels. Crop roots can follow these channels, which are coated with partly decayed organic matter, into the acid subsoil. Measurements of water infiltration with a Guelph permeameter and a methylene blue dye showed that such channels form the major infiltration sites during rainstorms. Implications for nitrogen use efficiency and cropping pattern are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010715
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...