Thesis (MScAgric)--Stellenbosch University, 1992. / One microfiche copy / ENGLISH ABSTRACT: The possibility of harvesting grapes at an earlier stage of maturity, based on
differences in glucose and fructose concentration which influence the sweetness of
grapes, was investigated. Although differences between cultivars were found the
extent was not such that a specific cultivar could be selected in order to harvest at a
lower sugar concentration, but with the same sweetness. Certain characteristics of
table and wine grape cultivars with respect to anatomical composition and skin
penetration resistance (SPR) were also investigated in order to ascertain the extent
to which grapes would resist external damage, and to what extent turgor and skin
thickness contributed to SPR. Daily variances in SPR confirm that not only skin
strength, but also the turgor of the grape berry contributed to SPR. Skin
penetration resistance seems to be a good criterion of the extent to which cultivars
would resist external damage, because it is based on the toughness of the skin and
the turgor of the berry. / AFRIKAANSE OPSOMMING: Die moontlikheid van vroeer oes op grond van verskille in die glukose- en fruktosekonsentrasie
wat 'n invloed op die soetheid van druiwe mag he, is ondersoek. Daar
is gevind dat die verskille wat tussen cultivars voorkom nie van so 'n grootte-orde is
dat 'n spesifieke cultivar geselekteer kan word ten einde by 'n laer totale suiker,
maar by dieselfde soetheidsgraad, te kan oes nie. Verder is sekere eienskappe van
tafel- en wyndruifcultivars t.o.v. anatomiese samestelling en doppenetrasieweerstand
(DP\V) ondersoek om die moontlike weerstand teen eksterne
beserings en die mate waartoe turgor en dopdikte 'n invloed daarop mag uitoefen,
_vas te stel. Daaglikse variasie in DPW het bevestig dat die DPW nie alleen
afhanklik is van dopsterkte nie, maar ook van die turgor van die korrel.
Doppenetrasieweerstand blyk 'n goeie maatstaf te wees vir die mate waartoe
cultivars weerstand hied teen sekere eksterne beserings omdat dit gebaseer is op
dopsterkte en turgor van die korrel.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/69667 |
| Date | January 1992 |
| Creators | Van Dyk, B. W. (Burger Wynand) |
| Contributors | Chambers, K. R., Goussard, P. G., Uys, D. C., Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology and Institute for Wine Biotechnology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | af_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 59 p. : ill. |
| Rights | Stellenbosch University |
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