Browsing by Author "Orffer, C. J."

Now showing 1 - 4 of 4
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    Changes in carbohydrates in nursery-grown grapevine rootstocks
    (South African Society for Enology and Viticulture, 1983) Uys, D. C.; Orffer, C. J.
    The utilisation and accumulation of sugar, starch and hemicellulose were studied in nursery-grown grapevine rootstocks. For an initial period lasting about 12 weeks all three components were utilised to varying degrees by the cuttings. Subsequently, starch and hemicellulose increased in the stem (original cutting) of the plant, while sugar remained low until the onset of winter. In the shoots, hemicellulose accumulation was very marked, whereas in the roots starch was the dominant carbohydrate component.
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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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    Symptomatology and anatomy of stemgrooving (legno riccio) in the grape vine
    (South African Society for Enology and Viticulture, 1980) Kriel, G. J. le R.; Orffer, C. J.; Beukman, E. F.
    External and anatomical differences between organs affected and unaffected by stemgrooving were studied on the wine grape cultivar Chenin blanc and the table grape cultivars Barlinka and Almeria. Cultivar susceptibility, graft transmissibility as well as the effect of the disease on the percentage of take and growth in: the nursery were studied. The probability of an association with other virus diseases was considered. Abnormal behaviour of the vascular cambium of infected vines gave rise to hypertrophy, hyperplasia, hypoplasia and parenchymatoses in the secondary xylem and phloem. In diseased tissues dift'erentiation of pbeDogen proceeded abnormally deep into the phloem rays. Graft transmission was detected anatomically within six months. The disease was found in all the vine growing districts of the Western Cape. Anatomical.studies showed that the disease had been present for many years. A negative effect on the percentage of t:'tKe and growth in the nursery was, recorded. A probable-relationship with corky bark was indicated anatomically and by indexing with LN33.