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Geology, particle size distribution and clay fraction mineralogy of selected vineyard soils in South Africa and the possible relationship with grapevine performanceVan Schoor, Lourens H. 03 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This study is an integral part of a multidisciplinary research project concerning the effects of
soil and climate on wine quality. The motive, which led to the setting up of this project, was
that producers could not determine beforehand whether a specific location would yield wines
of high or low quality. If a specific cultivar were to be planted at the wrong location, then it
was likely that wine of table quality would result, rather than the export quality wine that was
intended. The long term objectives of this multidisciplinary project were the compilation of
guidelines by means of which different sites may be classified according to their potential for
the production of high quality wines, and the identification of the most important climatic and
soil factors responsible for differences in wine quality and character. In this multidisciplinary
project, measurements (soil water, leaf water potential, cane mass and yield) were made
under dry land conditions in Sauvignon blanc vineyards at six different localities: five in the
Stellenbosch district (Simonsberg, Kuils River, Helshoogte, Papegaaiberg and Devon Valley)
and one in Durbanville. Each vineyard was owned by a private commercial producer. The
vines were approximately 10 years old in all cases, and were trained on a hedge system.
Measurements were made in plots, each of which contained 20 vines. Two different soil
types were identified at each locality. Vine growth and wine quality differed markedly on
these contrasting soils, even though they were located in close physical proximity. The
measurements that were made at high and low production plots at each locality during this
study were obtained from points which were not more than 60 m metres apart. An automatic
weather station was erected halfway between the two, contrasting, experimental plots.
Within the overall scope of the multidisciplinary project, the study which forms the subject of
this thesis, concentrated on the effects of soil parent material as a soil forming parameter and
as a possible predetermining character with regard to vine growth and wine character. From
literature it was clear at the outset of this work that the geology of the coastal wine region is
very complex and varies over short distances. The geological history indicates different types
of rock formation and rock forming process (sedimentary, igneous as well as metamorphic),
plate tectonic activity, mountain building, erosion and weathering, over a period of
approximately 1 000 million years. The present landscape includes a coastal plane, hills, and
eroding mountains.
Statistical analyses indicated that the soils from the different localities could mainly be
characterised in terms of differences in their sand size fractions. Soils from Durbanville are
dominated by fine sand and correlates with the underlying phyllitic shales. Soils from Kuils
River contain significantly more coarse sand when compared with the other sites. This
appears to be a reflection of the underlying coarse granitic material, and implies that in situ
weathering played an important role in soil development. .The data did not, however, prove
that the Kuils River soils formed solely from underlying rocks. The gravel and stone fraction for the Kuils River soils were nevertheless correlated with those of the underlying parent
material. Soils from Helshoogte and Simonsberg (both of which are underlain by granites),
Papegaaiberg and Devon Valley (both underlain by hornfels) were not significantly dominated
by any particular sand fraction. Soils from these localities therefore did not only reflect the
underlying material as a source of soil parent material. This implied mixing of parent material
and/or the incursion of eolian sand at Helshoogte, Simonsberg and Devon Valley. A marine
incursion may have affected the soil parent material at Papegaaiberg.
In order to obtain more information concerning the origins and possible mixing of parent
materials prior to and during soil formation, samples from the different soil horizons in each
profile were subjected to a chemical analysis. Particular emphasis was placed on potassium,
which is an extremely important nutrient mineral element, from the viewpoints of vine growth
and wine quality. Because the soils used in this study were all located in production
vineyards, the probability that fertiliser residues would have contaminated the soils was high.
The lower soil horizons were considered to be least affected by this contamination and
therefore most likely to be indicative of the natural soil chemical composition. However, the
lower horizon K content of the soils in this study could not be reliably correlated with any
known or predicted characteristic that might link the soil parent material with local rock types.
At Durbanville, both soils contained small quantities of K in the lower horizons, reflecting the
underlying phyllitic shales, but at Devon Valley and Papegaaiberg, the lower horizons
contained more K than expected. The soils at these localities are situated on hornfels,
containing low quantities of K. The large quantities of K in the soils may have indicated that
these soils are situated close to a granite/Malmesbury contact zone. Soils from Kuils River,
Simonsberg and Helshoogte are situated on K-rich porhyritic granites and it was expected
that these soils would contain relatively large quantities of K in the lower horizons. This,
however, was not the case. It was therefore concluded that dilution with K-poor material had
taken place. Such material could have been derived from higher-lying sandstones, or from
eolian processes during the Cenozoic. Alternatively, the K content of the soil might have
been depleted by long continued leaching.
A semi-quantitative analysis of the minerals in the soil clay fractions was also carried out.
The objective was to identify the clay minerals that were present in the different soil horizons
and to relate the minerals to weathering conditions. Evidence linking the minerals in the clay
fractions of the soil samples with the mineralogical composition of the soil parent materials
was sought. The clay fraction mineralogy data indicated that all soils in the study area are in
an advanced stage of weathering and are dominated by kaolinite, and in certain soils quartz.
It was difficult to relate these minerals directly with soil parent material because the primary
minerals originating from the soil parent materials have been extensively broken down. The
simultaneous presence of quartz and gibbsite in the clay fraction of both soils at Simonsberg,
Helshoogte and Durbanville as well as one soil form from bath Kuils River and Simonsberg, indicated non-uniform distribution of clay fraction minerals, indicating that different stages of
weathering were present during soil formation. This could have been a result of mixing of
parent materials, but may also reflect different periods of weathering of the same material.
Both soils at Papegaaiberg, both soils at Devon Valley and other soils at Simonsberg and
Kuils River indicated uniform clay fraction mineralogy distribution, mainly because the
absence of gibbsite is related to the presence of quartz in the clay fraction.
The soil characteristics, as determined in this study, were also compared with vine growth,
wine quality and wine character, as obtained in the broader multidisciplinary research project.
For most soils in this study, an increase in clay fraction kaolinite was associated with a
reduction in vegetative growth, overall wine quality, and fresh vegetative character. An
increase in clay fraction quartz was associated with higher overall wine quality. Increased
shoot growth also affected fresh vegetative character positively. Better growth occurred on
higher altitudes and this resulted, for Sauvignon blanc, in higher wine quality. Wines
produced from vines situated on both phyllitic shales and porhyritic granites showed high
quality (Durbanville and Helshoogte), but both were related to low clay fraction kaolinite
content and high altitude. It was not possible to relate parent material directly with vine
growth, wine quality and/or wine character. The lowest quality wines, however, were
produced from vines situated on hornfels (Papegaaiberg and Devon Valley), both containing
high quantities of clay fraction kaolinite and situated on low altitudes. High levels of K in soils
containing high levels of clay fraction kaolinite may have been partly responsible for low wine
quality obtained on such soils. / AFRIKAANSE OPSOMMING: Hierdie studie vorm 'n integrale deel van 'n multi-dissiplinêre navorsingsprojek oor die effek
van grond en klimaat op wynkwaliteit. Die motivering wat gelei het tot die beplanning van
hierdie projek, was dat produsente nie vooraf kon bepaal of 'n spesifieke lokaliteit wyne kan
produseer van hoë of lae kwaliteit nie. Indien 'n spesifieke kultivar op die verkeerde lokaliteit
geplant word, sou dit waarskynlik tot In gewone tafelwyn lei, instede van 'n wyn van
uitvoergehalte. Die langtermyn doelwitte van die multi-dissiplinêre projek was om riglyne te
ontwikkel om verskillende lokaliteite te klassifiseer na aanleiding van·hul potensiaal om hoë
kwaliteit wyne te produseer, asook om die belangrikste klimaats- en grondfaktore
verantwoordelik vir die produksie van hoê kwalitiet wyne te identifiseer. In hierdie multidissiplinêre
projek was metings (plant beskikbare water, blaarwater potensiaal, lootmassa en
oes) onder droêland toestande bepaal in Sauvignon blanc wingerde by ses verskillende
lokaliteite: vyf in die Stellenbosch distrik (Simonsberg, Kuilsrivier, Helshoogte, Papegaaiberg
and Devon Valley) en een in Durbanville. Elke wingerd is besit deur 'n kommersiêle
privaatprodusent. Die stokke was ongeveer 10 jaar oud in alle gevalle en opgelei op 'n
heining sisteem. Metings was in eksperimentele blokke van 20 stokke elk uitgevoer. Twee
verskillende grondtipes is by elke lokaliteit identifiseer. Lootgroei en wynkwaliteit het
merkbaar verskilop die kontrasterende gronde, selfs waar gronde nabyaanmekaar was. Die
metings is Liitgevoer op hoë- en lae produksie eksperimentele blokke waar gronde by
spesifieke lokaliteite nie verder as 60 meter was nie. 'n Outomatiese weerstasie was halfpad
tussen die twee kontrasterende grondtipes by elk van die ses lokaliteite opgerig.
Binne die algemene omvang van die multi-clissiplinêre projek, het die studie wat die
onderwerp van hierdie tesis is, gekonsentreer op die effek van moedermateriaal as
grondvormende parameter asook as moontlike voorspeller van wingerdgroei en wynkarakter.
Dit was duidelik uit die literatuur dat die geologie van die Wynkusstreek baie kompleks is en
oor kort afstande varieer. Die geologiese geskiedenis dui daarop dat verskillende tipes
gesteentes en verskillende prosesse van gesteente-vorming (sedimentêr, stollings- en
metamorfe), plaattektoniese aktiwiteit, orogenese, erosie en verwering, oor 'n periode van
ongeveer 1 000 miljoen jaar plaasgevind het. Die huidige landskap sluit kusvlaktes, heuwels
en geêrodeerde berge in.
Statistiese analises het aangetoon dat die gronde van die verskillende lokaliteite hoofsaaklik
in terme van verskille in sandgrootte fraksies onderskei kon word. Gronde van Durbanville is
gedomineer deur fyn sand en korreleer met onderliggende fillietiese skalies. Gronde van
Kuilsrivier bevat betekenisvol meer growwe sand wanneer dit vergelyk word met die ander
lokaliteite. Dit is waarskynlik afkomstig vanaf die onderliggende growwe granitiese materiaal
en impliseer dat in situ verwering 'n belangrike rol gespeel het in grondontwikkeling. Die data
het egter nie bewys dat die gronde van Kuilsrivier slegs uit die onderliggende graniete gevorm het nie. Die gruisfraksies in die gronde by Kuilsrivier was tog vergelykbaar met die
onderliggende materiaal. Gronde vanaf Helshoogte and Simonsberg (beide onderlê deur
graniete), Papegaaiberg and Devon Valley (beide onderlê deur hornfels) was nie betekenisvol
gedomineer deur 'n spesifieke sandfraksie nie. Gronde vanaf hierdie lokaliteite het dus nie
slegs die onderliggende gesteentes verteenwoordig nie. Dit dui op vermenging van
moedermateriaal en/of eoliese prosesse by Helshoogte, Simonsberg and Devon Valley. 'n
Styging in seevlak kon die moedermateriaal by Papegaaiberg beïnvloed het.
Om meer inligting omtrent die oorsprong en moontlike vermening van moedermateriaal voor
grondvorming te verkry, is die verskillende grondmonsters chemies ontleed. Kalium is In
uiters belangrike voedingselement wat lootgroei en wynkwaliteit kan beïnvloed. Aangesien
die gronde in hierdie studie in bestaande produksieblokke voorkom, was daar 'n goeie kans
dat bemestingstowwe die chemiese samestelling kon beïnvloed. Die C horisonte van die
verskillende gronde was beskou as dié wat die minste deur bemesting beYnvloedsou word en
die naaste aanduiding van natuurlike grondchemiese samestelling. Die C horison K-inhoude
van die gronde in die studie het egter nie gekorreleer met enige eienskap wat die
moedermateriaal van die gronde met die lokale gesteentetipe kon verbind nie. By
Durbanville, het beide gronde klein hoeveelhede K in die C horisonte bevat, wat die
onderliggende fillietiese skalies reflekteer, maar by Devon Valley en Papegaaiberg, het die C
horisonte meer K bevat as wat verwag is. Die gronde by hierdie lokaliteite word onderlê deur
hornfels, wat lae hoeveelhede K bevat. Die groot hoeveelhede K in hierdie gronde dui
moontlik op 'n kontaksone tussen graniet en Malmesbury gesteentes in die area. Gronde
vanaf Kuilsrivier, Simonsberg en Helshoogte word onderlê deur K-ryke porfiritiese graniete
wat groot hoeveelhede K in die ondergronde sou bevat. Dit was egter nie die geval nie en dit
was aanvaar dat verdunning van K-arme materiaal plaasgevind het. Die oorsprong van Karme
materiaal was waarskynlik vanaf hoêr-liggende sandstene, of vanaf eoliese prosesse
gedurende die Cenozoikum. Alternatiewelik is K inhoude van die gronde verlaag deur lang
en aanhoudende loging.
'n Semi-kwantitatiewe analise van minerale in die kleifraksie was uitgevoer om te bepaal
watter minerale in die kleifraksie van die verskillende gronde teenwoordig is en om die
minerale met stadia van verwering te vergelyk. Dan kon die mineralogiese samestelling in
verband met moedermateriaal gebring word. Resultate het aangetoon dat al die gronde in die
studie in 'n gevorderde stadium van verwering is en gedomineer word deur kaoliniet, en in
sekere gronde, klei fraksie kwarts. Aangesien die primêre minerale in 'n groot mate
afgebreek is, was dit moeilik om die minerale in die kleifraksie direk in verband met
moedermateriaal te bring. Die voorkoms van kwarts en gibbsiet in die kleifraksie in beide
gronde van Simonsberg, Helshoogte en Durbanville asook een grondvorm vanaf beide
Kuilsrivier en Simonsberg, het aangetoon dat verskillende stadia van verwering gedurende
grondvorming in hierdie gronde voorgekom het. Dit kan die gevolg wees van vermenging van verskillende moedermateriaal, maar kan ook verskillende periodes van verwering van
dieselfde materiaal aandui. Beide gronde by Papegaaiberg, beide gronde van Devon Valley
die ander gronde by Simonsberg en Kuilsrivier het slegs een fase van verwering tydens
grondvorming aangedui, hoofsaaklik as gevolg van die afwesigheid van gibbsiet wanneer
kwarts voorkom.
Grondeienskappe, soos bepaal in hierdie studie, was ook vergelyk met lootgroei, wynkwaliteit
en wynkarakter, soos verkry uit die resultate van die multi-dissiplinêre projek. Vir die meeste
gronde in die studie was 'n toename in kleifraksie kaoliniet geassosieer met afname in
vegetatiewe groei, algemene wynkwaliteit, asook vars vegetatiewe wynkarakter. 'n Toename
in kleifraksie kwarts was geassosieer met hoër algehele wynkwaliteit. 'n Toeneme in
vegetatiewe groei het ook die vars vegetatiewe karakter van die wyn positief beïnvloed. Beter
vegetatiewe groei het op hoër hoogtes voorgekom en dit het gelei tot hoër wynkwaliteit vir
Sauvignon blanc. Wyne afkomstig van wingerde op beide fillietiese skalies en porfiritiese
graniete, was van hoër kwaliteit (Durbanville and Helshoogte), maar beide was geassosieer
met lae kleifraksie kaoliniet en hoë ligging. Dit was nie moontlik om moedermateriaal direk
met vegetatiewe groei, wynkwaliteit en/of wynkarakter te vergelyk nie. Wyne met die laagste
kwaliteit kom egter voor op hornfels (Papegaaiberg and Devon Valley), wat beide groot
hoeveelhede kleifraksie kaoliniet bevat en geleê is op lae hoogtes. Hoê vlakke van K in
gronde wat groot hoeveelhede kleifraksie kaoliniet bevat kan gedeeltelik verantwoordelik
wees vir lae kwaliteit wyne op sulke gronde.
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The abundance and diversity of meso- and macrofauna in vineyard soils under different management practicesNel, Werner 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: The agricultural sector in South Africa relies heavily on the use of pesticides to protect
crops against pest organisms. Pesticides can affect non-target organisms such as the
meso- and macrofauna in the soil detrimentally. Since these organisms play an important
role in the processes of mineralization and decomposition in the soil and contribute to soil
fertility, it is important that they are protected. A large amount of published literature
exists on the biological importance of soil meso- and macrofauna and the effects that
various agricultural practices have on them.
The main aim of this study was to investigate the influence of agricultural practices on
the abundance and diversity of meso- and macrofauna in different vineyard soils. A
comparative study was conducted of an organically managed, conventionally managed
and an uncultivated control soil. A secondary aim was to determine the effect of these
agricultural management practices on the biological activity of these animals.
Soil samples were taken, from which mesofauna (Collembola and Acari) were extracted
with a modified Tullgren extractor, identified and counted. Earthworms were extracted
from the soil using hand sorting methods. Soil parameters such as pH, water holding
capacity, organic matter content, soil texture and soil respiration were determined. Bait
lamina and litter-bags were also used to help determine the biological activity within the
soil.
The mesofauna diversity was quantified using the Shannon Weiner diversity index, as
well as a diversity index described by Cancela da Fonseca and Sarkar (1996).
Differences in abundance of both the meso-and macrofauna were statistically measured
using ANOVA's. Biological activity results were also interpreted using ANOV A's.
Results indicate that the abundance of the meso fauna was the highest at the organically
treated vineyard soil and lowest in the conventionally managed soil where pesticide
application took place. The earthworms also showed the same trend as the mesofauna, but were much more influenced by seasonal changes. Biological activity, according to
the bait lamina and the litter-bag results, was higher in both the conventionally and
organically managed soils than in the control, but no statistical significant differences
were found between the two experimental soils. The soil respiration (C02-flux), also
indicating biological activity, was highest in the organically treated soil and lowest in the
conventionally treated soil.
The different sampling techniques used gave variable results and although the organically
managed soil proved to have higher abundances of both meso- and macrofauna, the
biological activity did not show the same trends. In conclusion the data did not give
enough evidence as to whether organic management practices were more beneficial than
conventional management practices for the maintenance of soil biodiversity. / AFRIKAANSE OPSOMMING: Die Suid Afrikaanse Landbousektor steun hewig op die gebruik van verskillende
chemiese pestisiede om oeste teen pes organismes te beskerm. Pestisiede kon ook
verskeie ander nie-teikenorganismes soos die meso- en makrofauna in die grond negatief
affekteer. Hierdie organismes behoort beskerm te word omdat hulle 'n belangrike rol
speel in grondprosesse soos mineralisering, en die afbreek van organiese materiaal.
Hierdie organismes dra ook by tot die vrugbaarheid van die grond. Daar is heelwat
gepubliseerde literatuur beskikbaar wat verband hou met die biologiese belangrikheid van
grond meso- en makrofauna en die effekte wat verskeie landbou behandelings op hulle
het.
Die primêre doel van hierdie studie was om vas te stel watter invloed konvensionele
landboupraktyke op die hoeveelheid en diversiteit van meso- en makrofauna in
verskillende wingerdgronde het. 'n Vergelykende studie is gedoen om wingerdgronde
wat konvensioneel en organies behandel is sowel as 'n onbehandelde kontrolegrond met
natuurlike plantegroei met mekaar te vergelyk. 'n Sekondêre doel van hierdie studie was
ook om die effek van die verskillende boerderymetodes op die biologiese akitiwiteit in
die grond te ondersoek.
Grondmonsters is geneem, waaruit die meso fauna (Collembola en Acari) deur middel van
'n aangepaste Tullgren ekstraktor ge-ekstraheer, geïdentifiseer en getel. Die erdwurms is
deur middel van handsorteringsmetodes versamel. Die volgende grond parameters is
gemeet: pH, waterhouvermoë, organiese materiaal inhoud, grondtekstuur en
grondrespirasie. "Bait lamina" en "litter bags" is ook gebruik om biologiese aktiwiteit in
die grond te bepaal.
Die diversiteit van mesofauna is bepaal met die Shannon Weiner diversiteitsindeks, as
ook 'n diversiteitsindeks wat deur Cancela da Fonseca en Sarkar (1996) ontwikkel is. Die
resultate van beide die meso- en makrofauna hoeveelhede in die verskillende
wingerdgronde is met mekaar vergelyk deur van ANOV A's gebruik te maak. Die resultate van die biologiese aktiwiteit is ook deur middel van ANOVO's statisties met
mekaar vergelyk.
Die resultate het aangetoon dat die hoeveelheid mesofauna die hoogste in die organies
behandelde grond en die laagste in konvensionele grond was. Die erdwurms het
dieselfde patroon as die mesofauna getoon, maar is baie meer deur seisoenale faktore
geaffekteer, bv. reënval. Volgens die resultate van die "bait lamina" en die "litter bags"
was die biologiese aktiwiteit in die grond hoër in beide die eksperimentele grond as in die
kontrolegrond. Die grondrespirasie (C02-puIs) was hoër in die kontrolegrond as in die
ander eksperimentele gronde.
Daar was groot variasie tussen die resultate wat met die verskillende tegnieke verkry is en
alhoewel die organiese perseel hoër hoeveelhede van beide meso- en makrofauna gehad
het, het die biologiese aktiwiteit nie dieselfde tendens gewys nie. Vanuit die data wat
verkry is kon daar dus nie met sekerheid afgelei word dat organiese boerderymetodes
beter vir die biodiversiteit van gronde,soos hier gemeet, is as konvensionele
boerderymetodes nie.
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Die effek van verskillende oppervlakbewerkingspraktyke op die wortelverspreiding van wingerdBrink, Daan 03 1900 (has links)
Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2007. / This study forms part of an ARC Nietvoorbij research project on the long-term effect of
different groundcover management practices in vineyards. This study concentrated on the
root distribution of the vines after different groundcover practices were used for one
decade.
The vineyard on the research farm of the Agricultural Research Council at Robertson,
South Africa, was divided into 56 equally distributed trail blocks, 14 treatments with four
replicas each. For the study Chardonnay cultivar on 99 Richter rootstock was used. This
study concentrated on only eight treatments. The eight different cover crop practices
consisted of the mechanical treatment, chemical treatment, straw mulch treatment,
permanent cover crop treatment and four annual cover crop treatments. The annual cover
crop treatments consisted of triticale cover crop that was sprayed with an herbicide before
bloom, a triticale cover crop that was left to die naturally, a grazing vetch cover crop that
was sprayed with an herbicide before bloom and a grazing vetch cover crop that was left
to die naturally. The vineyard was established in November 1992 while the different
treatments started in April 1993. Root studies were conducted during the 2002/2003
season.
In this study the auger method was used to determine root density (mm/cm³). The root
density was correlated with data from the penetrometer studies, yield and shoot mass
collected during the same season.
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The effects of fertilizers and irrigation upon exchangeable cations in a light alluvial vineyard soilPiaget, J. E. H. (Jean Edouard Henri) January 1953 (has links)
Thesis (MScAgric)--Stellenbosch University, 1953. / No Abstract Available
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The effect of atmospheric and soil conditions on the grapevine water statusLaker, Mareli S. (Mareli Susan) 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Due to the extraordinary drought resistance of the grapevine, viticulture without
irrigation in the winter rainfall coastal areas of South Africa is a feasible and
commonly used practice. Wine quality is largely determined by the quality of the
grapes from which it is made. Grapevine physiology is affected both directly and
indirectly by water stress, which may vary according to soil type and prevailing
atmospheric conditions. The water status of the grapevine can affect grape
composition profoundly, either directly or indirectly, in either a positive or negative
way, depending on the degree as well as the duration of water stress. There are
three important factors involved in the development of water stress, namely the
transpiration rate, the rate of water movement from the soil to the roots, and the
relationship of soil water potential to leaf water potential. All three these factors are
affected by atmospheric and/or soil conditions.
In warm winelands such as South Africa (Western Cape), with a mediterranean
climate which is characterised by a hot, dry summer period, the most important
characteristic of soil is its ability to supply sufficient water to the grapevine during the
entire growing season. Leaf water potential (Ψl) has gained wide acceptance as a
fundamental measure of grapevine water status, and has been widely applied in
viticultural research. Shortly before dawn, Ψl approaches equilibrium with soil water
potential and reaches a maximum daily value.
The study formed an integral part of a comprehensive, multi-disciplinary research
project (ARC Infruitec-Nietvoorbij Project No. WW13/01) on the effect of soil and
climate on wine quality, which commenced in 1993 and will be completed in 2004.
This study was conducted during the 2002/03 growing season in two Sauvignon
blanc vineyards situated at Helshoogte and Papegaaiberg, both in the Stellenbosch
district, approximately nine kilometres apart. Two experiment plots, representing
contrasting soil types in terms of soil water regime, were selected in each vineyard.
At Helshoogte the two soils represented the Tukulu and Hutton forms, and the soils
at Papegaaiberg were of the Avalon and Tukulu forms.
The aim of this study was to determine the effect of atmospheric conditions and
soil water status on the level of water stress in the grapevines for each soil at each
locality, as well as the effect of grapevine water stress on yield and wine quality. This
was done by determining and comparing the soil water status, soil water holding
capacity of the soils and the evapotranspiration of the grapevines on the two different
soils, at each of the two localities differing in mesoclimate and topography. The
atmospheric conditions at the two localities during the 2002/03 season were also
determined and compared to the long-term average atmospheric conditions, and the
level of water stress of grapevines on each soil at each locality was measured. During the 2002/03 growing season, atmospheric conditions were relatively warm
and dry in comparison to the long-term averages of previous seasons. These
conditions accentuated the effects of certain soil properties that may not come
forward during wetter, normal seasons.
The usually wet Tukulu soil at Helshoogte was drier than expected during the
2002/03 season compared to the Hutton soil. Due to more vigorous growth on the
Tukulu soil, grapevines extracted more soil water early in the season, leading to a
low soil water matric potential and more water stress in the grapevines. Due to the
higher vigour, resulting in more canopy shading, and more water stress, the dominant
aroma in wines from the Tukulu soil was fresh vegetative. The Hutton soil maintained
consistency with regards to both yield and wine quality compared to previous
seasons. On the other hand the Tukulu soil supported a higher yield, but with lower
than normal wine quality.
The Avalon soil at Papegaaiberg maintained the highest soil water potential
towards the end of the season, probably due to capillary supplementation from the
sub-soil. Grapevines on the Tukulu soil at Papegaaiberg experienced much higher
water stress than ones on the other three soils, especially during the later part of the
season. This could be ascribed to a combination of factors, the most important being
the severe soil compaction at a shallow depth, seriously limiting rooting depth and
root distribution, which is detrimental to grapevine performance.
Both the soil water status and atmospheric conditions played important roles in
determining the amount of water stress that the grapevines experienced at different
stages. The air temperature and vapour pressure deficit throughout the season were
consistently lower at Helshoogte, the cooler terroir, compared to Papegaaiberg, the
warmer terroir. At flowering, Ψl was lower for grapevines at Helshoogte than at
Papegaaiberg, showing that diurnal grapevine water status was primarily controlled
by soil water content. The difference in grapevine water status between the two
terroirs gradually diminished until it was reversed during the post harvest period when
Ψl in grapevines at Papegaaiberg tended to be lower compared to those at
Helshoogte. The relatively low pre-dawn Ψl at Helshoogte indicated that the
grapevines were subjected to excessive water stress resulting from the low soil water
content. However, grapevines at Helshoogte did not suffer material water stress (i.e.
Ψl < -1.20 MPa) during the warmest part of the day, suggesting that partial stomatal
closure prevented the development of excessive water stress in the grapevines.
This suggests that low pre-dawn Ψl values do not necessarily imply that
grapevines will experience more water stress over the warmer part of the day, or visa
versa. This does not rule out the possibility that side-effects of partial stomatal closure, such as reduced photosynthesis, can have negative effects on grapevine
functioning in general. These results also suggest that measurement of diurnal Ψl
cycles at various phenological stages is required to understand and quantify terroir
effects on grapevine water status. / AFRIKAANSE OPSOMMING: Danksy die droogteweerstand van die wingerdstok is die verbouing van wingerde
sonder besproeiing ‘n praktiese en algemene verskynsel in die winterreënval-areas
van Suid-Afrika. Wynkwaliteit word grootliks bepaal deur die kwaliteit van die druiwe
waarvan dit gemaak word. Wingerdfisiologie word direk en indirek beïnvloed deur
waterstres, wat kan varieer volgens die grondtipe en die heersende atmosferiese
toestande. Die waterstatus van die wingerdstok beïnvloed druifsamestelling, direk of
indirek, en positief of negatief, afhangend van die graad en tydsduur van die
waterstres. Daar is drie belangrike faktore betrokke by die ontwikkeling van
waterstres, naamlik die transpirasietempo, die tempo van waterbeweging vanaf die
grond na die wortels, en die verhouding tussen die grondwatermatrikspotensiaal tot
blaarwaterpotensiaal. Al drie die faktore word beïnvloed deur die atmosferiese en/of
grondtoestande.
In warm wynboulande soos Suid-Afrika (Weskaap), met ‘n meditereense klimaat
wat gekarakteriseer word deur ‘n warm, droë somerperiode, is die belangrikste
eienskap van grond die vermoë om voldoende water aan die wingerdstok te verskaf
gedurende die hele seisoen. Blaarwaterpotensiaal (Ψl) het wye aanvaarding bekom
as die fundamentele meting van wingerstokwaterstatus, en word wyd toegepas in
wingerdkundige navorsing. Kort voor sonsopkoms, nader Ψl ‘n ewewig met die
grondwatermatrikspotensiaal en bereik ‘n maksimum daaglikse waarde.
Die studie vorm ‘n integrale deel van ‘n omvattende, multi-dissiplinêre
navorsingsprojek (ARC Infruitec-Nietvoorbij Projek No. WW13/01) op die effek van
grond en klimaat op wynkwaliteit, wat in 1993 in aanvang geneem het en in 2004
afgehandel sal word. Hierdie studie is uitgevoer gedurende die 2002/03 seisoen in
twee Sauvignon blanc wingerde geleë by Helshoogte en Papegaaiberg, beide in die
Stellenbosch distrik, ongeveer nege kilometer van mekaar. Twee eksperimentele
persele, elkeen verteenwoordigend van kontrasterende grondtipes in terme van
grondwaterregime, is geselekteer in elke wingerd. By Helshoogte word die twee
gronde verteenwoordig deur die Tukulu en Hutton grondvorms, en die gronde by
Papegaaiberg is van die Avalon en Tukulu vorms.
Die doel van die studie was om die effek van atmosferiese toestande en
grondwaterstatus op die wingerdstok se waterstatus vir elke grond by die twee
lokaliteite te bepaal, sowel as die effek van die wingerdstok se waterstatus op die
opbrengs en wynkwaliteit. Dit is gedoen deur die grondwaterstatus, die
grondwaterhouvermoë, sowel as die evapotranspirasie van die wingerdstokke op die
twee verskillende gronde by elk van die twee lokaliteite, wat verskil in mesoklimaat
en topografie, te bepaal en vergelyk. Die atmosferiese toestande by die twee
lokaliteite gedurende die 2002/03 seisoen is ook bepaal en vergelyk met die langtermyn gemiddelde atmosferiese toestande. Die vlakke van waterstres in
wingerdstokke op elke grond by elke lokaliteit is ook gemeet.
Gedurende die 2002/03 groeiseisoen, was die atmosferiese toestande relatief
warm en droog in vergelyking met die langtermyn gemiddeldes van vorige seisoene.
Hierdie kondisies aksentueer die effek van sekere grondeienskappe wat nie
noodwendig na vore kom gedurende normale, natter seisoene nie.
Die gewoonlike nat Tukulu grond by Helshoogte was droër as verwag gedurende
2002/03 in vergelyking met die Hutton grond. As gevolg van sterker groekrag op die
Tukulu grond, het wingerdstokke meer grondwater onttrek vroeg in die seisoen, wat
gelei het tot ‘n lae grondwatermatrikspotensiaal en meer waterstres in die
wingerdstokke. Die sterker groeikrag het meer beskaduwing van die lower asook
meer waterstres veroorsaak, wat gelei het daartoe dat die dominante aroma in wyne
vanaf druiwe op die Tukulu grond vars vegetatief was. Die Hutton grond het
bestendig gebly in terme van opbrengs en wynkwaliteit in vergelyking met vorige
seisoene. Daarteenoor het die Tukulu grond ‘n hoër opbrengs gelewer, maar met laer
as gewoonlike wynkwaliteit.
Die Avalon grond by Papegaaiberg het die hoogste grondwatermatrikspotensiaal
behou tot die einde van die seisoen, heelwaarskynlik a.g.v. kapillêre aanvulling
vanuit die ondergrond. Wingerdstokke op die Tukulu grond by Papegaaiberg het
heelwat meer waterstres ondervind as op die ander drie gronde, veral later in die
seisoen. Dit kan toegeskryf word aan ‘n kombinasie van faktore, die belangrikse
daarvan die erge grondkompaksie vlak in die grond, wat worteldiepte en
-verspreiding ernstig beperk het, wat op sy beurt nadelig is vir wingerdprestasie.
Beide die grondwaterstatus en atmosferiese toestande het ‘n belangrike rol
gespeel in die bepaling van die hoeveelheid waterstres wat die wingerdstok op
verskillende stadiums ondervind het. Die lugtemperatuur en waterdampdruktekort
was regdeur die seisoen laer by Helshoogte, die koeler terroir, as by Papegaaiberg,
die warmer terroir. Gedurende blom was die Ψl laer vir wingerdstokke by Helshoogte
as by Papegaaiberg, wat daarop wys dat daaglikse wingerdstok waterstatus
hoofsaaklik deur die grondwaterinhoud bepaal was. Die verskil in wingerdstok
waterstatus tussen die twee terroirs het geleidelik verminder totdat dit omgekeer was
gedurende die na-oes periode toe Ψl in wingerdstokke by Papegaaiberg geneig het
om laer te wees in vergelyking met die by Helshoogte. Die relatiewe lae voorsonop Ψl
by Helshoogte het daarop gedui dat die wingerdstokke aan oormatige waterstres
onderwerp was. Die wingerdstokke by Helshoogte het egter nie materiële waterstres
(i.e. Ψl < -1.20 MPa) gedurende die warmste gedeelte van die dag ondervind nie, wat
aandui dat gedeeltelike huidmondjiesluiting plaasgevind het om die ontwikkeling van
oormatige waterstres te verhoed.Dit dui aan dat lae voorsonop Ψl waardes nie noodwendig impliseer dat
wingerdstokke meer waterstres gedurende die warmste gedeelte van die dag sal
ondervind nie, of visa versa. Dit sluit nie die moontlikheid uit dat negatiewe neweeffekte
van gedeeltelike huidmondjiesluiting, soos ‘n vermindering in fotosintese, ‘n
negatiewe effek kan hê op die wingerdstok se funksionering in die algemeen nie.
Hierdie resultate stel voor dat die meting van daaglikse Ψl siklusse gedurende
verskeie fenologiese stadia benodig word om die effek van terroir op die wingerdstok
se waterstatus te verstaan en te kwantifiseer.
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Die invloed van spesifieke grond en klimaats parameters op wingerdprestasie, wynkwaliteit en -karakterRoux, F. A. 03 1900 (has links)
Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2005. / This thesis forms part of a research program that is investigated by ARC Infruitec-
Nietvoorbij and the University of Stellenbosch. The aim of this program is to
quantify the effect of soil and climate on wine quality and character as a basis for
scientific demarcation of production regions. Natural factors are first quantified and
characterised so that relative homogeneous natural terroir units (NTU) can be
identified. Thereafter wines made from these different localities are assessed for
similarities which permit grouping of localities into viticultural terroirs.
The present study involved seven research plots in the Robertson district, making
use of initial measurements by ARC Infruitec-Nietvoorbij in the 2000/01 and
2001/02 seasons together with more intensive measurements in the 2002/03 and
2003/04. The seven plots are located in two wards, Le Chasseur and Vinkrivier.
Sauvignon blanc plots were marked at two localities, each with two sub-plots
occurring in one block. Three Cabernet Sauvignon plots were marked out. Two
plots occurred in one block in Le Chasseur and one plot in Vinkrivier. Plots within
the same block were located on different soil types so that the effect of soil type on
wine quality and character could be monitored. Morphological examination of soil
profiles at each plot was carried out together with physical and chemical analysis of
samples taken at 30cm depth intervals. Soil water content was measured at
regular intervals to assess soil water tension. Vineyard performance was assessed
in terms of phenology, root system studies, leafwaterpotential measurements,
canopy quality assessment, leaf analysis, shoot growth, and data relating to
ripening, harvest and pruning. Wines were made from each plot by ARC Infruitec-
Nietvoorbij and evaluated by a tasting panel after six months and then again after
eighteen months. Meteorological data were collected in each ward.
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Nutritional status of geologically different vineyards in HelderbergShange, Philisiwe Lawrancia 12 1900 (has links)
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.
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