Articles by Author: Johannes Van Der Westhuizen

Search results for Johannes Van Der Westhuizen

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  1. Measurement of exchangeable aluminium in soils and clay minerals by isotopic exchange

    Measurement of exchangeable aluminium in soils and clay minerals by isotopic exchange

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Isotopically exchangeable Al was determined in soils and clay minerals by equilibration with 28Al. Best results were obtained with a weak extractant and an equilibration time of eight min. The calculated amount of isotopically exchangeable Al was independent of the...
  2. The effect of sevoflurane induction on the myocardial performance index in healthy individuals

    The effect of sevoflurane induction on the myocardial performance index in healthy individuals

    Item type: Journal Article • Journal: Southern African Journal of Anaesthesia and Analgesia
    Background: The myocardial performance (Tei) index is a simple, reproducible and easily performed measure of cardiac performance. Its ease of use and proven clinical application make this an attractive measure perioperatively. For appropriate use of this index under sevoflurane anaesthesia,...
  3. An Ectomycorrhizal Fungus of Pine Seedlings in an Eastern Transvaal Nursery

    Item type: Journal Article • Journal: South African Forestry Journal
    Mycorrhizae of Pinus patula and P. elliottii seedlings were examined and the macroscopic, anatomic and scanning electron microscopic features described. The ectotroph in P. patula mycorrhizae was isolated, described and identified as Thelephora terrestris.
  4. Die invloed van verskillende veedigthede teen dieselfde veebeladings op die produksie van jong groeiende ossies op oshonagrasveld

    Die invloed van verskillende veedigthede teen dieselfde veebeladings op die produksie van jong groeiende ossies op oshonagrasveld

    ‘n Weidingsproef is uitgevoer in Oshonagrasveld in Ovambo om vas te stel wat die invloed van verskillende veedigt‐hede teen konstante veebeladings op die produksie van jong ossies is.
  5. Die benutting van grasveld indie sentrale oranje‐vrystaat met skape

    Die benutting van grasveld indie sentrale oranje‐vrystaat met skape

    ‘n Studie van die benutting van suiwer klimaks grasveld in die Sentrale Oranje‐Vrystaat deur skape het getoon dat skape wel voorkeur aan sekere plantspesies bo ander gee. Hierdie seleksiepatroon verander nie baie van die somer na die winter nie, tensy...
  6. Die invloed van snoei op koolsuurg asabsorpsie en koolhidraatinhoud van <em>ehrharta calysina</em> en <em>osteospermumsinuatum</em>

    Die invloed van snoei op koolsuurg asabsorpsie en koolhidraatinhoud van <em>ehrharta calysina</em> en <em>osteospermumsinuatum</em>

    Verwydering van 80% van die bogrondse massa (op ‘n varsmassa basis) van Ehrharta calycina (gras) en Osteospermum sinuatum (bossie) in onderskeidelik die vlagblaar en blomknopstadium het ‘n skerp daling in die totale netto CO2 absorpsie van die plante tot vegolg...
  7. Die invloed van snoei tydens antese op koolsuurgasabsorpsie en koolhidraatinhoud van <em>ehrharta calycina</em> en <em>osteospermum sinuatum</em>
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    Die invloed van snoei tydens antese op koolsuurgasabsorpsie en koolhidraatinhoud van <em>ehrharta calycina</em> en <em>osteospermum sinuatum</em> <sup>1</sup>

    Verwydering van onderskeidelik 40% en 80% van die bogrondse varsmassa van Ehrharta calycina (gras) en Osteospermum sinuatum (Karoobossie) tydens antese het ‘n afname in die totale netto CO2‐absorpsie, suikerkonsentrasie, styselkonsentrasie en totale beskikbare koolhidraatinhoud van die plante tot gevolg gehad,...
  8. Evaluering van braakstelsels vir droëlandkoringverbouing in die Oranje-Vrystaat

    Evaluering van braakstelsels vir droëlandkoringverbouing in die Oranje-Vrystaat

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Drie produksiestelsels vir droëlandkoring is te Glen en Bethlehem geëvalueer. Die kortbraak was vyf tot ses maande, intermediêre-braak was 12 tot 13 maande en langbraak was 17 maande. Glen verteenwoordig 'n semi-ariede somerreëngebied waar die proefgrond 'n plantbeskikbare-waterstoorkapasiteit van 148...
  9. Status of resistance to <em>Chilo partellus</em> (Lepidoptera: Pyralidae) in South African grain sorghum hybrids

    Status of resistance to <em>Chilo partellus</em> (Lepidoptera: Pyralidae) in South African grain sorghum hybrids

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The level of resistance to Chilo partellus was evaluated in 49 commercially available grain sorghum hybrids using artificial infestation in each of two field trials. The assessment of leaf feeding damage on a scale of one to nine indicated levels...