Articles by Author: Willem J Steyn

Search results for Willem J Steyn

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  1. Elucidation of seasonal pigmentation patterns in the involucral leaves of <em>Leucadendron</em> ‘Safari Sunset’

    Elucidation of seasonal pigmentation patterns in the involucral leaves of <em>Leucadendron</em> ‘Safari Sunset’

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    This study investigates seasonal pigmentation patterns found in the involucral leaves of Leucadendron ‘Safari Sunset’, with the long-term aim of colour manipulation. Treatments comprised deconed shoots and shoots in which the opening of the flower head was physically prevented. During...
  2. The function of regreening in yellow female <em>Leucadendron</em> (Proteaceae)

    The function of regreening in yellow female <em>Leucadendron</em> (Proteaceae)

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    What do female Leucadendron stand to gain by regreening their involucral leaves rather than discarding them after flowering? Regreening of involucral leaves could contribute to the carbon budget and/or protect the developing cone-shaped inflorescence during seed development. This was determined...
  3. Chemical thinning of ‘Barouni’ and ‘Manzanilla’ olives with naphthalene acetic acid under South African conditions

    Chemical thinning of ‘Barouni’ and ‘Manzanilla’ olives with naphthalene acetic acid under South African conditions

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Table olives grown in the Mediterranean-type climate of Western Cape province of South Africa are prone to alternate bearing, as elsewhere in the world. To date, South African producers have tolerated the negative effects of alternate bearing, but due to...
  4. Differential dependence of apple (<em>Malus domestica</em> Borkh.) cultivars on the xanthophyll cycle for photoprotection

    Differential dependence of apple (<em>Malus domestica</em> Borkh.) cultivars on the xanthophyll cycle for photoprotection

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The dependence of fruit peel photosystems of ‘Granny Smith’, ‘Braeburn’, ‘Fuji’, ‘Golden Delicious’ and ‘Topred’ apple (Malus domestica Borkh.) peel on the xanthophyll cycle for photoprotection was studied under laboratory conditions. Mature fruit peel was either treated with 1 mm dithiothreitol...
  5. Die invloed van verskillende waterregimes op Up-to-date aartappels I. Vegetatiewe ontwikkeling, fotosintesetempo en stomatadiffusieweerstand

    Die invloed van verskillende waterregimes op Up-to-date aartappels I. Vegetatiewe ontwikkeling, fotosintesetempo en stomatadiffusieweerstand

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Drie grondwaterregimes (20, 50 en 70% onttrekking van plantbeskikbare water) is gedurende herfsaanplan- tings in 1987 en 1988 op Up-to-date aartappels toegepas om die invloed daarvan op groei en ontwikkeling te ondersoek. Twee fisiologiese parameters van plantwaterstremming, naamlik, fotosintesetempo en...
  6. Die invloed van verskillende waterregimes op Up-to-date aartappels II. Opbrengs, grootteverspreiding, kwaliteit en waterverbruik

    Die invloed van verskillende waterregimes op Up-to-date aartappels II. Opbrengs, grootteverspreiding, kwaliteit en waterverbruik

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Drie besproeiingsbehandelings (20, 50 en 70% onttrekking van plantbeskikbare water) is toegepas ten einde die optimum peil van grondwateronttrekking by aartappels te bepaal. Die proef is gedurende die 1987 en 1988 herfsseisoene uitgevoer. Totale waterverbruik van behandelings is bereken en...
  7. Leaf characters of various tea clones in relation to quality

    Leaf characters of various tea clones in relation to quality

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The leaves of ten different tea clones were investigated to explore the possibility that structural differences exist between clones and that morphological characters relate to the quality of the infusion. Our results revealed a significant negative correlation between TF-values and...
  8. AMMI analysis of potato cultivar yield trials

    AMMI analysis of potato cultivar yield trials

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Potatoes, Solanum tuberosum (L), are cultivated in South Africa under a variety of different climates and seasons. The wide environmental variation encountered and the confirmed occurrence of genotype-environmental interaction necessitates the use of criteria, other than averages, in the evaluation...
  9. The effects of tillage systems on soil bulk density and penetrometer resistance of a sandy clay loam soil

    The effects of tillage systems on soil bulk density and penetrometer resistance of a sandy clay loam soil

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Concern has been expressed that reduced tillage systems may lead to excessive soil compaction, with a negative impact on crop growth. The objectives of this study were to determine the effects of different tillage systems, namely, minimum tillage (disc and...
  10. Fotosintesetempo en stomatadiffusieweerstand van aartappels soos beïnvloed deur waterstremming

    Fotosintesetempo en stomatadiffusieweerstand van aartappels soos beïnvloed deur waterstremming

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Die invloed van waterstremming in aartappelplante op netto fotosintesetempo en stomatadiffusieweerstand is tydens 'n herfsaanplanting ondersoek. Watertoediening is op 14, 28 en 42 dae na opkom gestaak om sodoende verskillende waterstremmingsperiodes tydens die groeiseisoen toe te pas. Hierdie Studie is...