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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 evaluation and management of different grasses and legumes as potential cover crops in the vineyards of South AfricaFourie, J.C. 03 1900 (has links)
Thesis (PhD(Agric) (Agronomy))--University of Stellenbosch, 2007 / A selection of species suitable for cover crop management in the different wine grape
regions is required to enable more producers to apply this environment friendly practice
in a sustainable manner as part of an integrated production strategy. The correct
management practice(s) to be applied to these species over both the short and long
term in a cooler and warmer wine grape region needed clarification.
The effect of seeding date on the dry matter production (DMP) and weed control efficacy
of seven grasses and sixteen legumes, as well as varieties of three of these species,
was determined during 1991 and 1992. The decomposition rate of the mulches was
determined. In the cooler climate of Stellenbosch (33o55'S, 18o52'E), the Medicago
species, subterranean clovers, pink Seradella and three Vicia species did not compete
effectively with the winter weeds if the weekly precipitation from mid-March to mid-May
(autumn) exceeded 18 mm. The two oat species, as well as rye and triticale produced
more than five t/ha of dry matter if the precipitation exceeded 18 mm per week. The
DMP of the above-mentioned species indicated that these species could be considered
for cover crop management in Lutzville (31o35'S, 18o52'E), if full surface irrigation of 18
mm per week could be applied for 10 weeks directly after sowing, followed by 18 mm
fortnightly. Seeding date had a significant effect on DMP in both regions. A highly
significant correlation (r = 0.85, p ≤ 0.0001) existed between the decomposition rate of
the mulches and the initial amount of dry matter present on the soil surface.
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Etude de la contamination par les pesticides des milieux eau, air et sols : développement de nouveaux outils et application à l’estuaire de la Gironde / Water, air and soils contamination by pesticides : development of new tools and application to the gironde estuary systemCruz, Justine Marie 26 October 2015 (has links)
Largement utilisés par l’agriculture intensive, les pesticides sont aujourd’hui présents dans les différents compartiments environnementaux et ce à un niveau mondial. Les recherches de ces travaux de thèse se sont plus particulièrement portées sur deux grandes thématiques, l’une liée à l’écodynamique des pesticides en Garonne estuarienne par la caractérisation des sources, la présence et le devenir des molécules, et l’autre sur leur transfert dans les compartiments eau, air et sols d’un château viticole. Des méthodes d’analyse simples et rapides à mettre en oeuvre ont été optimisées, tout en étant sensibles afin d’être compatibles avec l’étude des milieux faiblement contaminés.Les pesticides les plus fortement quantifiés dans les stations d’épuration (STEP) bordelaises sont le diuron, l’imidaclopride et le fipronil (≈ 50-100 ng.L-1). N’étant pas éliminés par les différents traitements, ils sont présents dans les rejets (apports de l’ordre du g.j-1) qui peuvent alors être une source de contamination pour le milieu. Si les pesticides majoritairement présents dans la Garonne sont le métolachlore et ses métabolites (≈ 10-800 ng.L-1), qui présentent des pics printaniers en lien avec l’application de la molécule, les pesticides caractéristiques de STEP sont également quantifiés. Les concentrations sont plus faibles (0,5-20 ng.L-1) et moins variables mais ne peuvent cependant pas être négligées, certaines molécules étant fortement toxiques même à faible concentration, comme le fipronil (PNEC = 0,77 ng.L-1).Les sols du château viticoles sont caractérisés par des pics printaniers (50-1000 ng.g-1) en pesticides en lien avec les applications, comme le boscalid ou l’azoxystrobine. Des molécules non utilisées depuis plusieurs années, comme le diuron, ont également été mis en évidence à plus faibles niveaux de concentrations (ng.g-1) et moins variables ce qui témoigne de la persistance de certaines molécules. Le compartiment atmosphérique est également caractérisé par des pics saisonniers en lien avec l’application et la volatilité des molécules, comme le folpel ou le chlorpyrifos-methyl. Des pesticides non utilisés par le château mais potentiellement appliqués par des exploitations voisines comme le métolachlore ont également été détectés, ce qui démontre bien du transport des molécules. Des pesticides interdits (diuron), non utilisés (métolachlore) et utilisés (boscalid) par le château ont été mis en évidence dans la nappe phréatique. / Intensive use of pesticides led to a widespread contamination of water, air and soils compartments. The present study focused on two main subjects, one based the ecodynamic of pesticides in Garonne River by characterization of sources, presence and outcome of these molecules and one other based on their transfer to air, water and soil compartments of a vineyard. Easy and fast methods of extractions were optimized although they were sensitive in order to be applied for mildly contaminated samples.Most quantified pesticides in Bordeaux wastewater treatment plants (WWTP) were diuron, imidaclopride and fipronil (≈ 50-100 ng.L-1). As treatments were not efficient to remove pesticides, effluents are a significant source for the Garonne River (daily discharge around 5 g). Even if major pesticides in Garonne River were metolachlor and its metabolites (≈ 10-800 ng.L-1) which showed spring peaks, typical WWTP pesticides were also quantified. Concentrations were lower (0,5 - 20 ng.L-1) and variable but they cannot be neglected as they can be highly toxic. Fipronil was for instance detected at concentrations sometimes exceeding its PNEC (0.77 ng.L-1).Vineyard soils were characterized by spring peaks of pesticides (50-1000 ng.g-1) that can be related to applications, like boscalid or azoxystrobine. Pesticides forbidden for a long time have also been detected, like diuron but in lower concentrations levels (ng.g-1) and less variable, that highlighted persistence of such molecule. Atmospheric compartment was also characterized by spring peaks than can be related to applications and molecule volatility, with the presence of folpet and chlorpyrifos-methyl. Pesticides non used by the vineyard were also detected such as metolachlor, which highleted the transport of such molecules. Forbidden (diuron), non-used (metolachlor) and currently used (boscalid) pesticides were detected in the aquifer.
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Influence of ripening grape compounds on behavioural responses of birdsSaxton, Valerie Patricia January 2004 (has links)
Vineyards in New Zealand suffer bird damage caused by several avian species, including blackbirds and silvereyes. The introduced European Blackbird takes whole grapes which reduces yield. The self-introduced Australasian Silvereye pecks on grapes, leaving them on the vine to be further attacked by fungi and bacteria, and the subsequent off-odours can cause grapes to be refused by the winery or to suffer a price-reduction. Bird control methods remain primitive and largely ineffective during the long ripening period of wine grapes. An ecologically sound method to manage and reduce bird pressure requires deeper understanding of why some birds eat grapes, especially since grapes are not particularly nutritious.
This work investigated the extent to which blackbirds and silvereyes are attracted by various compounds in ripening grapes. Since in natural grapes these compounds develop and change simultaneously, I developed an artificial grape in which a single parameter could be investigated. Artificial grapes (and sometimes nectar) were presented on a bird feeder table and the responses of birds to hexose sugars, the aromas 2-3-isobutylmethoxypyrazine and geraniol, tartaric and malic acids, grape tannins, and purple and green colour were recorded on timelapse video and analysed.
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Homological Illusions of Persistence and StabilityMorozov, Dmitriy 04 August 2008 (has links)
<p>In this thesis we explore and extend the theory of persistent homology, which
captures topological features of a function by pairing its critical values. The
result is represented by a collection of points in the extended plane called
persistence diagram.</p><p>We start with the question of ridding the function of topological noise as
suggested by its persistence diagram. We give an algorithm for hierarchically
finding such epsilon-simplifications on 2-manifolds as well as answer the question
of when it is impossible to simplify a function in higher dimensions.</p><p>We continue by examining time-varying functions. The original algorithm computes
the persistence pairing from an ordering of the simplices in a triangulation and
takes worst-case time cubic in the number of simplices. We describe how to
maintain the pairing in linear time per transposition of consecutive simplices.
A side effect of the update algorithm is an elementary proof of the stability of
persistence diagrams. We introduce a parametrized family of persistence diagrams
called persistence vineyards and illustrate the concept with a vineyard
describing a folding of a small peptide. We also base a simple algorithm to
compute the rank invariant of a collection of functions on the update procedure.</p><p>Guided by the desire to reconstruct stratified spaces from noisy samples, we use
the vineyard of the distance function restricted to a 1-parameter family of
neighborhoods of a point to assess the local homology of a sampled stratified space at
that point.
We prove the correctness of
this assessment under the assumption of a sufficiently dense sample. We also
give an algorithm that constructs the vineyard and makes the local assessment in
time at most cubic in the size of the Delaunay triangulation of the point
sample.</p><p>Finally, to refine the measurement of local homology the thesis extends the
notion of persistent homology
to sequences of kernels, images, and cokernels of maps induced
by inclusions in a filtration of pairs of spaces.
Specifically,
we note that persistence in this context is well defined,
we prove that the persistence diagrams are stable,
and we explain how to compute them.
Additionally, we use image persistence to cope with functions on noisy domains.</p> / Dissertation
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Ant management in Western Cape vineyards.Addison, Pia. 28 November 2013 (has links)
No abstract available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.
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Experiments to modify grape juice potassium content and wine quality on granite derived soils near Paardeberg /Agenbach, G. January 2006 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.
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Die invloed van bemesting en lowerbestuur op die kaliuminhoud en pH van Cabernet sap en wynEngelbrecht, G. P. 03 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: In an attempt to reduce the pH of juice and wine, different fertiliser applications and canopy
management practices were evaluated in a field trial. Fertiliser treatments consisted of no,
CaS04, Ca(OH)2, and MgS04 fertilisation. Canopy management was as follows: suckering
(leaving only two shoots per bearer), tipping, vertical shoot positioning and removal of lateral
shoots and yellow leaves in the bunch zone (Canopy 1); suckering (leaving three shoots per
bearer), vertical shoot positioning as well as topping (Canopy 2); vertical shoot positioning and
topping (Canopy 3). The field trial was conducted in the Paardeberg region on the farms
Meerlus and Kersfontein. The vineyard at Meerlus was Cabernet franc/R99 with a high
canopy density and a good root distribution, established on a sandy loam soil of granite origin,
with a low subsoil pH and a high K content. The vineyard at Kersfontein was Cabemet
Sauvignon/101-14 Mgt with a lower canopy density and a less extensive root distribution, also
established on a sandy loam soil of granite origin, but with a low top- and subsoil pH and a
higher K content.
Fertilisation had no significant influence on the K content of juice and wine. Fertilisation with
Ca and Mg reduced the pH of juice significantly in the case of Meerlus. In contrast, Mg
fertilisation increased the pH of juice significantly at Kersfontein. Lastly, fertilisation had no
significant effect on the pH of the wine. The K content of the juice at Meerlus was significantly
reduced by Canopy 3 in comparison with Canopy 1 and 2. However, in contrast with Canopy
1 and 3, Canopy 2 significantly increased the pH of juice at Meerlus. The K content of the
juice at Kersfontein was significantly reduced by Canopy 1, compared to Canopy 2 and 3, with
no significant effect on the pH of the juice. Canopy management had no significant effect on
wine pH. It appears to be possible to reduce the pH of juice in the case of Cabernet franc/99R, situated
on granite soils, by means of Ca and Mg fertilisation. Because Ca(OH)2 and MgS04
fertilisation increased the maturity of Cabernet Sauvignon/101-14 Mgt grapes, it was
impossible to evaluate the effect of fertilisation on the pH of juice at Kersfontein. The general
phenomenon that a high canopy density results in a high pH of juice and wine, was not
observed in this field trial. The possible reasons for this were the low canopy density of the
control plots, as well as the difference in maturity between canopy management treatments. / AFRIKAANSE OPSOMMING: In 'n poging om die pH van sap en wyn te verlaag, is die effek van verskillende bemesting- en
lowerbestuursfaktore in 'n veldproef geêvalueer. Bemesting het bestaan uit geen, CaS04,
Ca(OH)2 en MgS04 toediennings. Lowerbestuur was: suier tot twee lote per draer, tip,
vertikale lootposisionering, verwydering van sylote en geel blare in trossone (Lower 1); suier
tot drie lote per draer, top en vertikale lootposisionering (Lower 2); top en vertikale
lootposisionering met geen suier nie (Lower 3). Die veldproef is op twee plase nl. Meerlus en
Kersfontein, in die Paardeberg omgewing uitgevoer. Die wingerd by Meerlus was Cabernet
franc/R99 met 'n hoë lowerdigtheid en goeie wortelverspreiding, wat op 'n sandleemgrond van
graniet oorsprong met In lae ondergrond-pH en hoë K-inhoud gevestig is. Die wingerd by
Kersfontein het bestaan uit Cabernet Sauvignon/101-14 Mgt met 'n laer lowerdigtheid en
swakker wortelverspreiding, wat op In sandleemgrond van graniet oorsprong met In deurgaans
lae grond-pH en baie hoë K-inhoud gevestig is.
Bemesting het geen betekenisvolle invloed op die K-inhoud van sap en wyn gehad nie. By
Meerlus het Ca- en Mg-bemesting egter die pH van sap betekenisvol verlaag. In teenstelling
hiermee het Mg-bemesting die sap-ph by Kersfontein betekenisvol verhoog. Bemesting het
verder geen betekenisvolle invloed op die pH van wyn gehad nie. Lower 3 het die K-inhoud
van sap by Meerlus betekenisvol verlaag in vergelyking met Lower 1 en Lower 2. By
Kersfontein was die K-inhoud van sap by Lower 1 betekenisvollaer as by Lower 2 en Lower 3.
Teenoor Lower 1 en Lower 3 het Lower 2 'n betekenisvol hoër sap-pH by Meerlus tot gevolg
gehad. Lowerbehandelings het egter geen betekenisvolle invloed op die pH van wyn gehad
nie.
Die moontlikheid bestaan dus om die sap-pH van Cabernet franc/R99 op granietgrond
betekenisvol m.b.v. Ca- en Mg-bemesting te verlaag. Aangesien Ca(OH)2- en MgS04- bemesting die rypheidsgraad van Cabernet Sauvignon/101-14 Mgt se druiwe betekenisvol
verhoog het, was dit onmoontlik om die effek van bemesting op sap-pH by Kersfontein te
evalueer. Die algemene verskynsel dat 'n hoë lowerdigtheid tot hoë pH's in sap en wyn lei, is
nie in die proef ondervind nie. Die lae lowerdigtheid van die kontrole persele en die verskil in
rypheidsgraad tussen lowerbehandelings kan moontlik as rede hiervoor aangevoer word.
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Modélisation climatique à l’échelle des terroirs viticoles dans un contexte de changement climatique / Climate modeling at vineyard scale in a climate change contextLe Roux, Renan 08 December 2017 (has links)
À l’échelle d’un terroir viticole, le climat présente des variations significatives et joue un rôle important sur les caractéristiques des vins produits. L’adaptation de la filière viticole au changement climatique en cours nécessite la connaissance de l’évolution du climat à l’échelle locale. Cette étude vise à intégrer cette échelle dans les projections climatiques en se basant sur l’utilisation combinée de modèles dynamiques et géostatistiques. Dans un premier temps, l’utilisation d’un modèle climatique régional à haute résolution (1 km) dans les vignobles de Marlborough (Nouvelle-Zélande) a permis de cartographier les températures d’une région viticole. Les limites et les incertitudes de l’utilisation de ce type de modèle, notamment pour la représentation des variations thermiques les plus locales, ont également été étudiées. Par l’utilisation des données issues d’un réseau dense de capteurs de température, une seconde étape a consisté au développement d’un modèle statistique non linéaire permettant une cartographie fine des températures sur les appellations Saint-Émilion, Pomerol et leurs satellites. Enfin une méthode d’intégration de l’échelle locale dans les projections de changement climatique est proposée, associant modèles dynamiques et modèles géostatistiques. Cette thèse a mis en évidence que l’utilisation simultanée de différentes méthodes de modélisation des températures peut représenter une piste intéressante pour pallier aux manques qu’elles peuvent représenter individuellement et limiter ainsi l’incertitude. / At vineyard scale, climate variability can be significant in magnitude and play a key role in vine and wine characteristics. Adaptation of viticulture to climate change requires knowledge about future fine-scale climate evolution. This study aims to integrate local scale in future climate projections, coupling dynamic and statistical modelling. A first step consisted in producing temperature maps at 1 km resolution using WRF in a vineyard area (Marlborough, New-Zealand) and evaluating model uncertainties. It revealed that dynamical models do not represent well local climate variations. Using a high density temperature data logger network, the second part is dedicated to developing a non-linear statistical model to map temperature at very fine scale in famous sub-appellations of the Bordeaux vineyard area (Saint-Émilion). Following, a method, coupling dynamical and statistical modelling, is proposed to integrate local scale in climate change projections. This thesis highlights that using simultaneously statistical and dynamical models can be an approach to reduce model uncertainties.
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