Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Little scientific information regarding the effect of different geological parent materials on
grapevine performance is currently available in South Africa. This aspect is of special
significance for the Helderberg area, where parent material may change from granite to shale
over a short distance. This results in shale- as well as granite-derived soils often occurring
within the same vineyard. The objectives of this study were to (i) quantify the nutritional status
and other soil properties of different parent materials (shale and granite) and overlying soils (ii)
investigate the impact of geological differences in the soil on the vine nutritional status and
certain vine parameters. This study was done over two seasons (2006/2007 and 2007/2008).
Two Sauvignon blanc and two Cabernet Sauvignon vineyard blocks were selected at two
different localities for each cultivar in the Helderberg area, South Africa. Shale- and granitederived
soils were identified within each block.
Kaolinite was the dominant mineral, whereas quartz and feldspar were sub-dominant. Traces of
mica were also present in some shale- and granite-derived soils. Granite- contained significantly
higher contents of coarse sand than shale-derived soils, whilst the opposite occurred in terms of
fine sand. These differences affected the water holding capacity, in general making it higher in
shale- than granite-derived soils. Shale-derived soils had higher concentrations of total K but
granite-derived soils had a higher ability to release K as they contained higher concentrations of
soluble K. The Q/I parameters, potential buffering capacity of K (PBCK) and equilibrium activity
ratio of K (ARK) showed no consistent responses to geological differences.
Potassium concentrations were higher in the leaf blades (obtained before harvest in 2007) from
Sauvignon blanc grapevines on granite- than on shale-derived soils. Potassium concentrations
in the Cabernet Sauvignon juice (obtained in 2007) tended higher in juice from granite- than
from shale-derived soils. In 2008, K concentrations tended higher in juice from shale- than from
granite-derived soils for both cultivars. The pH of the Sauvignon blanc juice (obtained in 2008)
tended higher in juice from shale-than from granite-derived soils, thus corresponding with the K
concentrations in the juice in this season. Nitrogen concentrations were higher in Cabernet
Sauvignon juice (obtained in 2007) and Sauvignon blanc juice (obtained in 2008) from shalethan
from granite-derived soils. In terms of vine water status, vines on granite-derived soils
appeared more stressed than those on shale-derived soils in both seasons at one of the
vineyards.
In these Sauvignon blanc and Cabernet Sauvignon vineyards, the K nutritional status was not
affected by geology in a consistent manner but there were some noticeable tendencies for a
specific cultivar during certain seasons. On account of vines being planted on shale- and
granite-derived soils within the same block, soil preparation was done similarly for both soils,
and they were exposed to similar irrigation schedules, canopy management strategies and
climatic conditions. Therefore, there is a high probability that all these practices may have
negated the effect of geology on the K status of soils and especially on juice K concentration at
the time of harvest. It was clear that seasonal differences and fertilisation affected the nutritional
status of the vines more than geology. / AFRIKAANSE OPSOMMING: In Suid-Afrika is daar tans min wetenskaplike inligting oor die effek van verskillende geologiese
moedermateriale op die prestasie van wingerd beskikbaar. Hierdie aspek is veral van belang in
die Helderberg-area, waar moedermateriaal oor ‘n baie kort afstand van graniet na skalie kan
wissel. Dit lei daartoe dat skalie-, sowel as granietgronde, dikwels binne dieselfde wingerd
voorkom. Die doelwitte van die studie was om: (i) die voedingstatus en ander grondkundige
eienskappe van die verskillende moedermateriale (skalie en graniet) en oorliggende gronde te
kwantifiseer (ii) die impak van geologiese verskille in die grond op wingerd se voedingstatus en
sekere wingerdkundige parameters, te ondersoek. Hierdie studie is oor twee seisoene
(2006/2007 en 2007/2008) gedoen. Twee Sauvignon blanc en twee Cabernet Sauvignon
wingerdblokke is geselekteer by twee verskillende lokaliteite vir elke kultivar in die Helderbergarea,
Suid-Afrika. Beide skalie- en granietgrond is binne elke blok geïdentifiseer.
Kaoliniet was die dominante mineraal, met kwarts en veldspaat sub-dominant, terwyl spore van
mika ook in beide skalie- en granietgronde gevind is. Granietgronde het betekenisvol hoër
hoeveelhede growwe sand bevat, terwyl skaliegronde meer fyn sand bevat het. Hierdie verskille
het ‘n effek op waterhouvermoë gehad en daartoe gelei dat waterinhoude oor die algemeen
hoër was vir skaliegronde. Skaliegronde het groter hoeveelhede totale K bevat, maar
granietgronde se vermoë om K vry te stel was hoër, omdat hulle ‘n hoër konsentrasie oplosbare
K bevat het. Die Q/I parameters, potensiële buffervermoë vir K (PBCK) en ewewig
aktiwiteitsverhouding vir K (ARK), is nie op ‘n konsekwente wyse deur geologiese verskille
beïnvloed nie.
Vir die Sauvignon blanc wingerde was kalium konsentrasies in blaarskywe (gemonster voor oes
in 2007) hoër vir graniet- as vir skaliegronde. Kalium konsentrasies in die sap vanaf Cabernet
Sauvignon (gemonster in 2007) het hoër geneig vir granietgronde. In 2008 het die kalium
konsentrasies, vir beide kultivars, hoër geneig in sap vanaf skaliegronde. Gedurende dié
seisoen het die pH van sap ook hoër geneig vir Sauvignon blanc vanaf skaliegronde, wat dus
ooreenstem met die K inhoud van die sap. Stikstof konsentrasies was hoër in sap vanaf
skaliegronde vir Cabernet Sauvignon (2007) en vir Sauvignon blanc (2008). In terme van die
wingerde se waterstatus, het stokke op die granietgrond, by een van die lokaliteite, geneig om
gedurende beide seisoene onder groter stremming te wees op graniet as op skaliegrond.
In hierdie Sauvignon blanc en Cabernet Sauvignon wingerde, is K voedingstatus nie op ‘n
konsekwente wyse deur geologie geaffekteer nie, maar gedurende sommige seisoene was daar
wel duidelike tendense vir ‘n spesifieke kultivar. Omdat die stokke binne dieselfde blok op
skalie- en graniet gronde geplant is, was grondvoorbereiding eenders vir die twee grondtipes
terwyl besproeiingskedule, lowerbestuur en klimaatstoestande ook identies was. Daar is dus ‘n
hoë waarskynlikheid dat al hierdie faktore daartoe kon bygedra het dat die effek van geologie
op die K status van van gronde versluier is, veral die effek op die K inhoud van sap teen oestyd.
Dit was duidelik dat seisoenale klimaatsverskile en bemestingspraktyke ’n groter effek as
geologie op die voedingstatus van die wingerd gehad het.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2603 |
| Date | 12 1900 |
| Creators | Shange, Philisiwe Lawrancia |
| Contributors | Fey, M. V., Conradie, W. J., Raath, P. J., University of Stellenbosch. Faculty of Agrisciences. Dept. of Viticulture and Oenology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | University of Stellenbosch |
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