Browsing by Author "Swanepoel, J. J."

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    A comparative anatomical study of the grapevine shoot : I Epidermis
    (South African Society for Enology and Viticulture, 1984) Swanepoel, J. J.; De la Harpe, A. C.; Orffer, C. J.
    Material gathered from three positions on the shoot and cane during veraison and two weeks after harvest were investigated for taxonomic features concerning the epidermis. Stomata and lenticels were present in all the cultivars studied, but trichomes were frequently present only on 99 Richter. Based on epidermal characteristics a dendogram giving the percentage similarity between cultivars, was constructed, and from this was concluded that concerning taxonomic features on Vitis vinifera L. cultivars tend to have a more than 90% similarity irrespective of the position on the shoot.
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    A comparative anatomical study of the grapevine, shoot and cane : II: periderm and secondary phloem
    (South African Society for Enology and Viticulture, 1984) Swanepoel, J. J.; De la Harpe, A. C.; Orffer, C. J.
    The taxonomic value of ten periderm and secondary phloem features of canes of different grapevine species was investigated. A scatter diagram showed that with few exceptions the American cultivars have a larger periderm with smaller secondary phloem, while the reverse was true for European cultivars. Crosses tend to cluster with one of their parents. It has been found that the largest intercultivar variation occurs at either the middle of the shoot length or the ventral sides of the basal part of the shoots.
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    The effect of trellis systems on the performance of vitis vinifera L. cvs. sultanina and chenel in the Lower Orange River Region
    (South African Society for Enology and Viticulture, 1990) Swanepoel, J. J.; Hunter, J. J.; Archer, E.
    The effect of six trellis systems on the reproductive and vegetative performance of Sultanina and Chene), grown in the lower Orange River region of South Africa, was investigated. Larger trellis systems significantly increased the yield of both cultivars, and the photosynthetic activities of the leaves at veraison as well as the canopy light environment tended to be higher for these systems. The higher yields recorded for Sultanina were attributed to improved budding percentages, which were caused by improved light environments at the basal 'buds. The improved yield obtained for Chene! however, was due to higher bunch masses, which were most likely caused by the higher photosynthetic activities of the leaves.