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The effects of girdling on shoot growth of Thompson seedless grapevinesSibbett, George Steven, 1940- January 1965 (has links)
No description available.
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Vegetative growth measurements and correlations of Cardinal grapevinesWahsh, Wahib Tawfick, 1938- January 1963 (has links)
No description available.
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The basis of variation in the size and composition of grape berries / John D. Gray.Gray, John D. January 2002 (has links)
Additional articles by author bound in back. / Bibliography: leaves 136-149 / ix, 150 leaves : ill., (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This investigated focussed on selected aspects of berry development and ripening that were subject to variation. Shiraz and Chardonnay were chosen as experimental varieties because these cultivars presented a large range of variability in the field. The extent of the variation within each of the recorded berry parameters was assessed using the coefficient of variation (CV), a unitless measure of sample variability relative to the sample mean, ideally suited to comparative studies. / Thesis (Ph.D.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 2002
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The basis of variation in the size and composition of grape berriesGray, John D. January 2002 (has links) (PDF)
"Department of Horticulture, Viticulture and Oenology, Faculty of Agriculture and Natural Resource Sciences, The University of Adelaide, Waite Campus, Glen Osmond S.A." Bibliography: leaves 136-149 This investigated focussed on selected aspects of berry development and ripening that were subject to variation. Shiraz and Chardonnay were chosen as experimental varieties because these cultivars presented a large range of variability in the field. The extent of the variation within each of the recorded berry parameters was assessed using the coefficient of variation (CV), a unitless measure of sample variability relative to the sample mean, ideally suited to comparative studies.
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A biochemical study of budbreak and plant growth regulators in table grapesLombard, Petrus Johannes 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The cultivation of table grapes in the warmer areas of South Africa, indeed worldwide, is
complicated by rest breaking problems in spring due to delayed budbreak. In order to
overcome these problems rest breaking agents, mainly hydrogen cyanamide, are applied.
However, instead of alleviating the problem, additional problems such as uneven
budbreak and reduced production are often induced. This study was initiated to further
understand the physiological processes occurring during budbreak and how the
application of hydrogen cyanamide influences these processes. The following aspects
were investigated in this study:
a. The effect of hydrogen cyanamide on tissue cytokinin (specifically zeatin
riboside) levels of Sultanina table grape vines after application at different times before
natural budbreak was studied over two seasons.
In 1997, hydrogen cyanamide was applied at three weeks before induced
budbreak and in 1998 at six weeks before induced budbreak. One year-old canes were
sampled weekly after hydrogen cyanamide application, divided into distal and proximal
sections, then further divided into buds, bark and wood tissues and the zeatin riboside
(ZR) levels determined. A relatively high amount of chilling coupled to late hydrogen
cyanamide application in 1997 led to a large effect on ZR release, but did not lead to
significant shifting of the budbreak pattern. Zeatin riboside peaks were observed in buds,
internode wood and bark of treated vines compared to control vines. The peaks were
higher in distal portions compared to proximal portions in all tissues. The relatively lower
chilling and earlier application of hydrogen cyanamide in 1998 had a larger effect on the
budbreak pattern while the bud ZR peak was shifted earlier. The distal portion bud ZR
. peak was again higher than the proximal portion bud ZR peak. In 1997, as sampling was
not initiated early enough, bud ZR peaks were only observed after budbreak, while in
1998 bud ZR peaks were observed before and after budbreak. The effect of these ZR
increases on the development of inflorescence primordia, subsequent bunch
development and ultimately production, are discussed.
b. Free xylem sap was sampled at cane and spur pruned lengths from unpruned
canes of Sultanina from budswell until after budbreak in 1999 and from three table
grape cultivars, i.e Sultanina, Alphonse Lavalleé and Sunred Seedless, in 2001 and ZR
levels determined. The ZR levels in the buds of these three table grape cultivars, pruned
to different cane lengths were also determined. One year old canes of these cultivars,
were each pruned to long canes (14 buds) and short spurs (2 buds). The ZR content in
buds of these canes at distal and proximal positions were determined weekly from
budswell until after budbreak in 1999. Xylary ZR peaks occurred before 50% budbreak. Spur xylary ZR levels of all
three cultivars followed a similar pattern, although at lower ZR levels than that of the
canes. This is similar to previous studies on xylary ZR levels of apple shoots. The high
levels of free ZR found in xylem sap at the distal portions of canes support the
hypothesis of a cumulative ZR build-up effect as cane length increases. Spur pruning
resulted in earlier budbreak and a higher final budbreak than cane pruning. The proximal
portions of shoots, whether spur pruned or the proximal portions of canes, showed
elevated ZR levels in all cultivars. This difference in ZR levels in bud tissue of different
portions of the cane would suggest a difference in ZR consumption or turnover.
The results of this study have important management implications for the cultivation of
vines in warmer areas in which hydrogen cyanamide is used to alleviate budbreak
problems. / AFRIKAANSE OPSOMMING: Die verbouing van tafeldruiwe in die warmer gebiede van Suid-Afrika, soos straks
wêreldwyd, word bemoeilik deur rusbreekprobleme in die lente weens vertraagde bot.
Rusbreekmiddels, meestal waterstofsiaanamied, word gevolglik toegedien om hierdie
probleme te probeer oorkom. In plaas van opheffing van die probleem, veroorsaak
hierdie toedienings somtyds addisionele probleme soos ongelyke bot en verlaagde
produksie. Hierdie studie is aangepak om die fisiologiese prosesse wat tydens bot
plaasvind, beter te verstaan, asook hoe die toediening van waterstofsiaanamied hierdie
prosesse beïnvloed. Die volgende is in hierdie studie ondersoek:
a. Die invloed van waterstofsiaanamied op lootweefsel sitokinien (naamlik zeatin
ribosied, ZR) vlakke van 'n Sultanina tafeldruif wingerd is oor twee seisoene ondersoek
na toediening op verskillende tye voor bot.
Waterstofsiaanamied is in 1997 drie weke en in 1998 ses weke voor
geïnduseerde bot toegedien. Een jaar oue lote is weekliks gemonster na
waterstofsiaanamied toediening, verdeel in apikale en basale gedeeltes en verder verdeel
in ogies, bas en houtweefsel en die ZR vlakke bepaal. Relatief hoër vlakke koue, gekoppel
met later watersiaanamied toediening het in 1997 tot 'n groot effek op ZR vlakke gelei,
maar het nie die botpatroon wesentlik verskuif nie. Zeatin ribosied pieke is waargeneem
in ogies, internode hout en bas van behandelde wingerd in vergelyking met kontrole
wingerd. Die pieke was hoër in apikale gedeeltes in vergelyking met basale gedeeltes in
alle weefsels. Die relatief laer koue en vroeër toediening van waterstofsiaanamied in 1998
het 'n groter effek op die botpatroon gehad, terwyl die ogie ZR piek vroeër geskuif is. Die
apikale gedeelte se ogie ZR piek was weereens hoër as die basale gedeelte se ogie ZR
piek. Monstering was nie vroeg genoeg begin in 1997 nie, aangesien ogie ZR pieke slegs
na bot waargeneem is, terwylogie ZR pieke in 1998 voor en na bot waargeneem is. Die
effek van hierdie verhoging in ZR vlakke op die ontwikkeling van blom primordia,
daaropvolgende tros ontwikkeling en uiteindelik produksie, is bespreek.
b. Vry xileemsap is gemonster van langdraer en kortdraer gedeeltes van
ongesnoeide lote van Sultanina vanaf ogieswel tot na bot in 1999 en vanaf drie tafeldruif
kultivars, naamlik Sultanina, Alphonse lavalleé en Sunred Seedless, in 2001 en die ZR
vlakke bepaal. Die ZR vlakke van ogies van hierdie drie kultivars, gesnoei tot verskillende
lootlengtes is ook bepaal. Eenjarige lote van hierdie kultivars is gesnoei tot langdraers
(14 ogies) en kortdraers (2 ogies). Die ZR vlakke in ogies geleë op apikale en basale
gedeeltes van hierdie lote is weekliks in 1999 bepaal vanaf ogieswel tot na bot
Xileemsap ZR pieke is waargeneem voor 50% bot. Kortdraer xileemsap ZR
vlakke het 'n soortgelyke patroon as die langdraers gevolg vir al drie kultivars, alhoewel teen laer ZR vlakke as die langdraers. Hierdie waarneming is soortgelyk aan vorige
studies op xileemsap ZR vlakke van appel lote. Die hoë ZR vlakke gevind in die xileemsap
van die apikale gedeeltes van lote ondersteun die hipotese van 'n kumulatiewe opbou van
ZR soos die lengte van die loot toeneem. Die snoei van lote as kortdraers het gelei tot
vroeër bot en 'n hoër finale bot persentasie as die snoei van langdraers. Die basale
gedeeltes van lote het verhoogde ZR vlakke in al drie kultivars getoon, onafhanklik van
die feit dat dit vanaf die kortdraer of die basale gedeelte van 'n langdraer was. Hierdie
verskil in ZR vlakke in ogie weefsel van verskillende gedeeltes van die loot impliseer 'n
verskil in ZR verbruik of omset.
The resultate van hierdie studie het belangrike bestuursimplikasies vir die verbouing van
wingerd in warmer gebiede, waar waterstofsiaanamied gebruik word om botprobleme te
oorkom.
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Physiological implications of partial defoliation of the grapevine (Vitis vinifera L. cv. Cabernet Sauvignon)Hunter, Jacobus Johannes 03 1900 (has links)
Thesis (PhD) -- Stellenbosch University, 1991. / ENGLISH ABSTRACT: The effect of partial defoliation as canopy management practice on metabolism and grape
composition of the grapevine, Vitis vinifera L cv. Cabernet Sauvignon, was investigated. The
establishment of physiologically sound principles on how to overcome deleterious effects
associated with vigorous and dense-canopy vines is emphasized. Experimental vines were
defoliated 33 % and 66 % evenly over the whole canopy from different developmental stages in
a field study. Effects on canopy microclimate, photosynthesis, photosynthate translocation,
vegetative growth, reproductive growth, root development and distribution, as well as grape and
wine quality, were determined. A method for the simultaneous extraction of sugars and organic
acids from freeze-dried berries at different developmental stages is described.
Partial defoliation of vines improved canopy microclimate and photosynthetic efficiency of
remaining leaves. Normal translocation and distribution patterns of photosynthates were
apparently unaffected by partial defoliation. Translocation to and accumulation of photosynthetic
products in the leaves and bunches of partially defoliated vines were, however, improved.
Remaining leaves of partially defoliated vines were in comparison photosynthetically more active.
Apart from a less favourable canopy microclimate, it seemed that the sink capacity of
non-defoliated vines did not comply to the source capacity, inducing a reduced rate of
photosynthesis.
Normal sigmoidal growth patterns of vines were not affected by partial defoliation as applied in
this study. This is important for the longevity, healthiness and productivity of vines. Vegetative
growth was differentially affected by partial defoliation. No compensatory leaf growth occurred in
reaction to partial defoliation from different developmental stages. Main shoot length, however,
decreased slightly. Lateral shoot length and number of laterals increased, whereas cane mass
decreased when vines were partially defoliated, particularly the earlier and more severe the
defoliation. Reproductive growth in terms of yield was deleteriously affected by 33 % defoliation
prior to pea size and 66 % defoliation prior to veraison. Budding percentage was, however,
improved by 33 % and 66 % defoliation, whereas bud fertility was only improved by 33 %
defoliation. Partial defoliation changed the canopy microclimate to conditions favourable for pest
and disease control and higher grape quality.
Subterranean growth was favourably affected by partial defoliation, particularly when applied from
pea size stage. These changes included higher root densities, development of higher numbers
of fine and medium diameter roots and occurrence of higher total root numbers in all soil layers.
Generally, defoliations from pea size and veraison were more efficient regarding root
development than defoliations from just after bud break and from berry set. Partially defoliated vines reacted by forming new roots, creating a more efficient nutrient absorption capacity and
utilization of soil and available water and that, together with higher photosynthetic activities of
leaves, provided an efficient mechanism for continued high performance.
Grape quality was not affected markedly by partial defoliation. Total soluble solids in berries of
defoliated vines were comparable to and even significantly higher than those of non-defoliated
vines in some cases, in spite of much lower leaf areas. Generally, total titratable acidity of musts
was also slightly higher for partially defoliated vines. Glucose and fructose concentrations in
berries were unaffected by partial defoliation, while tartaric acid concentrations were slightly
increased and malic acid concentrations slightly decreased. Partial defoliation generally
increased the anthocyanin concentration of berry skins. These changes in grape composition
suggest higher grape quality and seemed to result from improved light conditions in the canopy
interior. Berry volume decreased with partial defoliation, which lowered the pulp:skin ratio.
These berries are more desirable for quality wines. Regardless of severity or the developmental
stage defoliation was commenced, wine cultivar character and overall wine quality were
significantly improved.
Partial defoliation changed the general metabolism of vines, mainly in terms of more favourable
source:sink ratios, resulting in more efficient photosynthesis, subterranean performance and
canopy microclimate. In general, the results suggest that an even removal of 33 % of leaves
opposite and below bunches during the period from flowering or berry set to pea size stage may
be applied. lt is further suggested that existing vigorous and dense-canopy vines be 33 %
defoliated evenly on the lower half of the shoot (canopy) from pea size or veraison. This
hypothesis proved effective in improving canopy microclimate, photosynthetic activity and yield,
while vegetative growth was inhibited. Grape and wine quality were higher.
On the whole, partial defoliation as applied in this study, is recommended as canopy
management practice in order to facilitate the abolishment of deleterious effects of excessive
vegetative growth and canopy density on balanced metabolic activity, fruit and wine quantity and
quality, as well as longevity and healthiness of grapevines. / AFRIKAANSE OPSOMMING: Die invloed van blaarverwydering as loofbestuurspraktyk op die metabolisme en
druifsamestelling van die wingerdstok, Vitis vinifera L cv. Cabernet Sauvignon, is ondersoek. Die
vestiging van fisiologies-betroubare beginsels oor hoe nadelige effekte geassosieerd met geil en
lower-verdigte wingerde uitgeskakel kan word, word beklemtoon. Proefstokke is in 'n
veldondersoek 33 % en 66 % eweredig oor die hele lower vanaf verskillende
ontwikkelingstadiums ontblaar. Effekte op lowermikroklimaat, fotosintese, translokasie van
fotosintetiese produkte, vegetatiewe groei, reproduktiewe groei, wortelontwikkeling en
verspreiding asook druif- en wynkwaliteit is bepaal. 'n Metode vir die gelyktydige ekstraksie van
suikers en organiese sure uit gevriesdroogde korrels op verskillende groeistadiums is ontwikkel.
Blaarverwydering het lowermikroklimaat verbeter en fotosintetiese doeltreffendheid van
oorblywende blare op die stok verhoog. Normale translokasie en verspreidingspatrone van
produkte van fotosintese is skynbaar nie deur blaarverwydering befiwloed nie. Translokasie na,
en akkumulering van fotosintetiese produkte in die blare en druiwe van gedeeltelik ontblaarde
stokke, is egter verbeter. Oorblywende blare van gedeeltelik ontblaarde stokke was fotosinteties
meer aktief. Afgesien van 'n ongunstiger lowermikroklimaat, het die sinkkapasiteit van
nie-ontblaarde stokke skynbaar ook nie teen die bronkapasiteit opgeweeg nie en is 'n verlaagde
tempo van fotosintese verkry.
Normale sigmofdale groeipatrone van die stokke is nie deur blaarverwydering befrivloed nie. Dit
is belangrik vir langlewendheid, gesondheid en produktiwiteit van stokke. Vegetatiewe groei is
differensieel deur blaarverwydering befrivloed. Geen kompenserende blaargroei het in reaksie
op blaarverwydering vanaf verskillende ontwikkelingstadiums voorgekom nie. Hooflootlengte
was egter effens korter. Sylootlengte en aantal sylote het toegeneem, terwyl lootmassa
afgeneem het met blaarverwydering, veral hoe vroeer en strawwer dit toegepas is.
Reproduktiewe groei in terme van opbrengs is nadelig befrivloed deur 33 % ontblaring voor
ertjiekorrelstadium en 66 % ontblaring voor die deurslaanstadium. Botpersentasie is egter deur
blaarverwydering verbeter, terwyl oogvrugbaarheid slegs deur 33 % ontblaring verbeter is.
Blaarverwydering het 'n gunstige lowermikroklimaat vir die beheer van plae en siektes en hoer
druifkwaliteit geskep.
Ondergrondse groei is gunstig deur blaarverwydering befrivloed, veral wanneer toegepas vanaf
ertjiekorrelstadium. Hierdie veranderinge het ingesluit hoer worteldigtheid, ontwikkeling van
groter hoeveelhede wortels met 'n fyn en medium deursnit en die voorkoms van 'n groter aantal
totale wortels in alle grondlae. Blaarverwydering vanaf ertjiekorrel- en deurslaanstadia was in die algemeen meer doeltreffend ten opsigte van wortelontwikkeling as blaarverwydering vanaf net
na bot en vanaf korrelset. Gedeeltelik ontblaarde stokke het gereageer deur nuwe wortels te
vorm, waardeur 'n meer doeltreffende vermoe tot voedingstofopname en benutting van grand an
beskikbare water verkry is. Tesame met hoer fotosintetiese aktiwiteite van die blare is 'n
doeltreffende meganisme vir aanhoudende hoe prestasie verkry.
Druifkwaliteit is nie aanmerklik deur blaarverwydering beirwloed nie. Totale oplosbare stowwe in
druiwe van gedeeltelik ontblaarde stokke was vergelykbaar en selfs betekenisvol hoer as die van
nie-ontblaarde stokke in sekere gevalle, ten spyte van die baie laer blaaroppervlakte. In die
algemeen was die totale titreerbare suur in die mos van gedeeltelik ontblaarde stokke oak effens
hoer. Glukose- en fruktosekonsentrasies in die druiwe is nie deur blaarverwydering beinvloed
nie. Die konsentrasie wynsteensuur is egter effens verhoog en die appelsuurkonsentrasie effens
verlaag. Antosianienkonsentrasie van korreldoppe is in die algemeen deur blaarverwydering
verhoog. Hierdie veranderinge in druifsamestelling dui op hoer druifkwaliteit en is skynbaar die
resultaat van verbeterde ligtoestande in die binnekant van die lower. Korrelvolume het
afgeneem met blaarverwydering. Dit het die pulp:dop verhouding verlaag. Sulke korrels is meer
gewens vir bereiding van kwaliteitswyne. Wyn cultivarkarakter en totale wynkwaliteit is
betekenisvol deur blaarverwydering verhoog, onafhanklik van die strafheid of
ontwikkelingstadium waarvandaan blare verwyder is.
Blaarverwydering het die algemene metabolisme van die wingerdstok verander, hoofsaaklik ten
opsigte van meer gunstige bron:sink-verhoudings en derhalwe meer doeltreffende fotosintese,
ondergrondse groei en lowermikroklimaat. Die resultate dui in die algemeen daarop dat 'n
eweredige blaarverwydering van 33 % regoor en onderkant die trosse tydens blomvorming of
korrelset tot ertjiekorrelstadium toegepas kan word. Die resultate dui verder daarop dat 33 %van
bestaande geil en lower-verdigte stokke se blare eweredig verwyder kan word op die onderste
helfte van die loot (lower) vanaf ertjiekorrel- of deurslaanstadium. Hierdie hipotese was
suksesvol in die verbetering van lowermikroklimaat, fotosintetiese aktiwiteit en oesmassa.
Vegetatiewe groei is gestrem. Druif- en wynkwaliteit was hoer.
In die geheel kan blaarverwydering soos toegepas in hierdie ondersoek aanbeveel word as
loofbestuurspraktyk ten einde die uitskakeling van nadelige effekte van oormatige vegetatiewe
groei en lowerdigtheid op gebalanseerde metaboliese aktiwiteit, druif- en wynkwantiteit en
kwaliteit, asook langlewendheid en gesondheid van wingerdstokke te bevorder.
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Chemical regulation of growth and fruit maturity of Vitis vinifera 'Flame Seedless' using hydrogen cyanamideMayles, Karen Marie, 1957- January 1987 (has links)
The effect of hydrogen cyanamide (H₂CN₂) on budbreak and fruit maturity of 2-year old 'Flame Seedless' table grapes was investigated in a low desert climate in central Arizona. Dormant sprays of H₂CN₂ applied at 2.5 and 5.0% (v/v) concentrations hastened budbreak by at least 16 days with subsequent advancement of fruit maturity by 5 to 10 days. A 5.0% (v/v) dormant application of H₂CN₂ to whole vine, buds only or pruning cuts only advanced budbreak by at least 16 days and advanced fruit maturity by 1 to 5 days, regardless of application site. A more uniform budbreak was observed on H₂CN₂ treated vines, regardless of concentration or site of application when compared to control vines.
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A study of within-vineyard variability with conventional and remote sensing technologyStrever, Albert E. 12 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: In the past it was very difficult to visualise the extent and distribution of variability in growth
vigour within vineyards. The advancement of remote sensing technology has changed this
however, establishing new methods to assess and manage variability. Even though the
causes and effects of within-vineyard variability in growth vigour are complex, new
technologies offer better ways of monitoring, researching and managing these factors. In
addition to the possible benefits of aerial or satellite remote sensing, new methods of
mapping soil spatial variability as well as advances in georeferencing technologies supply
precision tools to both researchers and producers. The scientific advancement of the
technology, however, is currently the most important aspect needed. This is crucial to
answer and explore fundamental questions regarding the use of the technology and the
interpretation of results within the framework of the plant's observed reaction. Only then
can the possible applications in vineyard management be optimised to address the
management problems of extensive within-vineyard variation in growth vigour. The choice
will always be to use the technology to manage the observed variability in order to limit the
negative impacts of a heterogeneous harvest, or to identify the variability and its causes
for the implementation of management practices aimed at a more homogenous vineyard
and harvest. Whatever the case, extensive research is needed to provide tight correlations
between information gathered with new technologies to assess variability and plant status,
such as multi- and hyperspectral analysis, and ground-truthed results in the vineyard. Only
then will it become evident which methods and analyses would be useful in the drive
towards in-depth analysis and management of vineyards within the concept of precision
viticulture and its derived advantages.
With this in mind, the aim of this study was to establish an experimental model to use
remote sensing technologies to identify and classify within vineyard variability with a
subsequent analysis of the causes of variability and the effects on the plants. The targeted
experimental model was a vineyard with highly heterogeneous above-ground growth. An
aerial photograph of the vineyard was studied and manipulated to yield image pixel values
used to quantify the degree of variability for different plots, which were chosen according
to different plot layouts. Soil conditions were assessed on both a global and plot level, with
extremely high pH and low resistance values in the soil in combination with erratic soil
preparation practices found to be the main cause of variability. Soil physicochemical
condition was also assessed during a soil profile pit study. Significant differences were
found between several soil-related parameters measured for the higher and lower vigour
levels and a strong correlation was also found between the resistance of a saturated soil
paste and the image pixel values.
Vegetative measurements also yielded highly significant differences between the
vigour levels and confirmed the suitability of the vineyard to study within-vineyard variability. Some of these measurements were also strongly correlated with soil conditions
as well as image pixel values. Trunk circumference proved to be an excellent measure for
the level of variability, being linked strongly to canopy characteristics, soil conditions as
well as the image pixel values. Leaf water potential measurements also yielded significant
differences between the vigour levels.
Harvest data and wine analyses showed the effect that vigour differences can have on
grape composition and wine quality, even though the differences found here were much
less than expected. Even though no clear preference was shown between the wines made
from the different vigour levels, the lower vigour wine was considered fruitier. The overall
quality of both experimental wines was however very high, considering that experimental
winemaking techniques has been used.
Hyperspectral measurements also confirmed differences between the vigour levels
through a narrow-band NOVI (normalised difference vegetation index). It was also possible
to show differences in certain biochemical compounds between the vigour levels on both a
leaf and canopy level. Wavelength regions corresponding to carotenoid, chlorophyll a and
chlorophyll b showed different spectral reactions in the leaves of more stressed (lower
vigour) canopies, indicating possibilities for further studies.
This study and its results is the first of its kind in the South African wine industry and
paves the way for more focussed and in-depth analyses of the use of specifically multiand
hyperspectral data to accurately assess within-vineyard vigour variability and the
management thereof to yield optimum quality grapes for a specific wine target. Moreover,
the approach adopted in this study is also echoed in other international research programs
in prominent wine countries. The availability of scientific research regarding the optimal
use and limitations of these technologies has the potential to revolutionise production
management practices in the next few years in the viticultural industry. / AFRIKAANSE OPSOMMING: In die verlede was dit baie moeilik om die omvang en verspreiding van groeikragvariasie
binne 'n wingerd te visualiseer. Die vordering gemaak op die gebied van
afstandswaarneming-tegnologie het egter nuwe metodes beskikbaar gestel waardeur
hierdie variasie in wingerde gemonitor en bestuur kan word. Selfs al is die oorsake en
invloede van binne-wingerd-groeikragvariasie kompleks, verskaf nuwe tegnologieë
verbeterde metodes om hierdie variasie te monitor, te bestuur en na te vors. Saam met die
moontlike voordele wat lugfoto's en satelliet-afstandswaarneming teweegbring, verskaf
nuwe metodes om ruimtelike variasie in grondfaktore te karteer, asook vordering in geoverwysingstegnologie,
presisiehulpmiddels aan produsente én navorsers. Die
wetenskaplike vordering van dié tegnologie is tans van groot belang. Die belang daarvan
is om fundamentele vrae te ondersoek en te beantwoord rakende die gebruik van die
tegnologie en die interpretasie van resultate binne die raamwerk van die waargeneemde
reaksie in die plant. Dit sal die weg baan vir optimale toepassing van die tegnologie in
wingerdbestuur om sodoende die bestuursprobleme wat deur binne-wingerdgroeikragvariasie
teweeggebring word, aan te spreek. Die voorkeurkeuse is om dié
tegnologie aan te wend om hierdie variasie te bestuur sodat die negatiewe impak van In
heterogene oes teengewerk kan word, of om die variasie te identifiseer vir die
implementering van bestuurspraktyke gemik op die skep van 'n meer homogene wingerd
en oes. Dit is noodsaaklik dat uitgebreide navorsing gedoen word om noue verwantskappe
vas te stel tussen inligting wat ingewin is met behulp van nuwe tegnologieë wat die
variasie in plantstatus monitor, soos multi- en hiperspektrale analise, en inligting wat op
grondvlak ingewin is. Hieruit sal dit duidelik wees watter metodes en analises die
doeltreffendste is vir in-diepte analises en die bestuur van wingerde binne die konsep van
presisie-wingerdkunde.
Met inagneming van hierdie aspekte, was die doel van hierdie studie om 'n
eksperimentele model daar te stel waardeur afstandswaarneming-tegnologie gebruik kan
word om variasie binne wingerde te identifiseer en te klassifiseer deur analises van die
oorsake van hierdie variasie en invloede op die plant. Die geteikende eksperimentele
model was 'n wingerd met hoogs heterogene bogrondse groei. 'n Lugfoto van die wingerd
is bestudeer en gemanipuleer om pixelwaardes te verskaf wat die graad van variasie vir
verskillende eksperimentele plotte, wat aan die hand van verskillende plotuitlegte gekies
is, te kwantifiseer. Grondtoestande is bestudeer op 'n globale én plotvlak, met uiters hoë
pH en lae weerstande in kombinasie met verkeerde grondvoorbereidingspraktyke, wat
geïdentifiseer is as die hoofoorsake vir die hoë vlakke van variasie. Grondfisiese en
-chemiese toestand is ook tydens profielgatstudies bestudeer. Betekenisvolle verskille is
gevind tussen verskeie grondverwante parameters gemeet vir plotte met onderskeidelik laer en hoër groeikrag, en 'n sterk verwantskap is gevind tussen grondweerstand en
pixelwaardes, soos vanaf die lugfoto bepaal.
Vegetatiewe metings het ook betekenisvolle verskille tussen die hoër en laer
groeikragvlakke opgelewer, wat die geskiktheid van die wingerd vir die studie van binnewingerdvariasie
in groeikrag bevestig het. Van hierdie metings was ook nou verwant aan
grondtoestande, asook beeldpixelwaardes. Stamomtrek was 'n uitstekende maatstaf vir
die vlakke van variasie, aangesien dit nou verwant was aan lowertoestande,
grondtoestande, asook beeldpixelwaardes. Blaarwaterpotensiaal-metings het ook
betekenisvolle verskille tussen die hoër en laer groeikragvlakke opgelewer.
Oesdata en wynanalise het die uitwerking van groekragverskille op druifsamestelling
en wynkwaliteit uitgewys, selfs al was die verskille wat gevind is minder as wat verwag is.
Hoewel geen duidelike voorkeur tussen die wyne afkomstig van verskillende
groeikragvlakke uitgewys kon word nie, was die wyn wat van die laer-groeikrag stokke
gemaak was, meer vrugtig. Die algemene kwaliteit van beide wyne was egter baie hoog as
in ag geneem word dat eksperimentele wynmaakprosedures gevolg is.
Hiperspektrale metings het ook die verskille tussen groeikragvlakke bevestig deur 'n
nou-bandwydte NDVI ("normalised difference vegetation index"). Dit was ook moontlik om
verskille in sekere biochemiese komponente tussen die groeikragvlakke op 'n blaar- én
lowervlak uit te wys. Golflengte-areas ooreenstemmend met karotenoïed, chlorofil a en
chlorofil b het verskillende spektrale reaksies in die blare met hoër stresvlak (laer
groeikrag) lowers ten toon gestel. Dit het moontlikhede vir verdere navorsing uitgewys.
Hierdie studie en die resultate wat verkry is, is die eerste van sy soort in die Suid-
Afrikaanse wynbedryf. Dit baan die weg vir meer gefokusde en in-diepte analise van die
gebruik van spesifiek multispektrale en hiperspektrale data om binne-wingerdgroekragvariasie
akkuraat te monitor en te bestuur met die oog op optimum wynkwaliteit
vir 'n spesifieke produkdoelwit. Die aanslag van hierdie navorsing is ook sigbaar in ander
prominente wynproduserende lande. Beskikbaarheid van wetenskaplike navorsing
rakende die optimale gebruik en tekortkominge van hierdie tegnologieë het die potensiaal
om produksiebestuurspraktyke in die wingerdbedryf in die komende jare te
revolusionaliseer.
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The effect of shoot heterogeneity on the physiology and grape composition of Shiraz/Richter 99 grapevinesCloete, Hanle 12 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The effect of shoot heterogeneity on vegetative and reproductive growth parameters, vine
physiology and grape composition was investigated in a ShirazlRichter 99 vineyard.
Comparisons between underdeveloped (typically shorter and less ripened at véraison) and
normally developed shoots in both shaded (non-manipulated) and well-exposed (manipulated)
canopies were made. Compared to underdeveloped shoots, normal shoots had a larger total leaf
area, due to the higher occurrence of secondary shoots as well as larger leaves on primary and
secondary shoots. Since the photosynthetic activity of the leaves from normal shoots was higher
than those from underdeveloped shoots, higher levels of carbohydrates were produced and
stored in the former. Starch was more evenly distributed over the length of the whole shoot in
normally developed shoots compared to underdeveloped shoots. Normally developed shoots
were longer and thicker in diameter than underdeveloped shoots. The larger clusters of the
normally developed shoots are evidence of their more favourable total leaf area per gram berry
mass. Berries from the normally developed shoots were smaller at five weeks after véraison than
those from underdeveloped shoots, displaying a higher skin to pulp ratio and therefore higher
anthocyanin and total phenolic extraction potential for winemaking. The smaller clusters and
fewer berries per cluster found for the underdeveloped shoots indicate an imbalance between
vegetative and reproductive growth initiated during the vegetative growth phase and continued
during the ripening period.
The peculiar absence of statistically significant differences in grape composition between
normally and underdeveloped shoots indicates that assimilates needed for berry ripening of the
latter originated in organs other than the leaves [e.g. from adjacent normal shoots and the rest of
the permanent structure of the vine (cordon, trunk, roots)]. The larger differences in berry size
that occurred between shoot types in the shaded compared to the well-exposed canopies may be
evidence for this. The photosynthetic activity of shoots was lower in shaded than in exposed
canopies. The total carbohydrate production of the normal shoots in shaded canopies seemed
insufficient to supply in the ripening needs of the shoot itself, their own clusters as well as the
ripening of stem tissue and clusters of the underdeveloped shoots in the canopy. This is
illustrated by the lower levels of starch that accumulated in the normal shoots from shaded
compared to that of exposed canopies. Vine shoot heterogeneity clearly leads to visible and
physiological imbalances that would impact negatively on grape and wine quality as well as
production costs and should therefore be avoided on any terroir. / AFRIKAANSE OPSOMMING: In hierdie studie is die effek van heterogene lootontwikkeling in die lower van 'n ShirazlRichter 99
wingerd ondersoek. Vergelykings is getref tussen normale en onderontwikkelde lote in
beskadude en blootgestelde lowers ten opsigte van hul vegetatiewe en reproduktiewe groeieienskappe,
fisiologiese aktiwiteit en druifsamestelling en -gehalte. 'n Groter totale
blaaroppervlak het by die normaalontwikkelde lote voorgekom as gevolg van die groter aantal
sekondêre lote en groter primêre en sekondêre blare. Aangesien die blare van die normaal
ontwikkelde lote fotosinteties meer aktief was as dié van onderontwikkelde lote, het die
eersgenoemde lote groter hoeveelhede koolhidrate geproduseer en gestoor. Styselopberging het
meer eweredig oor die lengte van die normale lote plaasgevind. Laasgenoemde lote was ook
heelwat langer en dikker in deursnee as die onderontwikkelde lote. Die gunstiger totale
blaaroppervlak per korrelmassa verhouding van die normale lote is duidelik weerspieêl in die
groter trosse, terwyl die kleiner korrels (en dus die groter dop:pulp verhouding) op 'n groter
potensiaal vir kleur- en fenolekstraksie tydens die wynbereidingsproses dui. Die kleiner trosse en
kleiner aantal korrels per tros wat by die onderontwikkelde lote gevind is, dui op 'n wanbalans
tussen die vegetatiewe en reproduktiewe groei van die loot wat tydens die vegetatiewe groeifase
van die wingerdstok geïnisieer is en tydens die rypwordingsperiode voortgesit is.
Die vreemde afwesigheid van enige statisties betekenisvolle verskille in druifsamestelling tussen
die normale en onderontwikkelde lote dui daarop dat die verbindings wat vir die rypmaking van
trosse op onderontwikkelde lote aangewend is, waarskynlik van ander wingerdorgane (bv.
naasliggende lote, kordonarms, stam, wortels) as die spesifieke loot se blare afkomstig was. Die
waarneming dat die korrelgroottes van normale en onderontwikkelde lote meer van mekaar
verskil het in die beskadude as blootgestelde lowers, kan moontlik as bewys hiervoor dien. Die
fotosintetiese aktiwiteit van beide loottipes was laer in die skaduryke lowers. Die koolhidrate wat
deur normaalontwikkelde lote in skadu-Iowers geproduseer is, was oênskynlik onvoldoende vir
die rypmaking van die loot self, die spesifieke loot se trosse, asook die trosse en lootweefsel van
naasliggende onderontwikkelde lote. Hierdie bewerings word gerugsteun deur die laer vlakke
van styselakkumulasie wat by die normale lote in beskadude lowers gevind is. Aangesien
heterogene lootontwikkeling en -groei duidelike sigbare en fisiologiese wanbalanse in die
wingerdstok tot gevolg het wat negatief op druifsamestelling, wyngehalte en produksiekoste
inwerk, behoort dit in kommersiêle wingerde vermy te word.
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The effect of arbuscular mycorrhizal colonisation on the C economy, growth and nutrition of young grapevinesMortimer, Peter Edward 04 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Arbuscular mycorrhizal (AM) C-costs in grapevines were investigated. Since both
dormant vines and AM colonisation rely on stored C for initial growth, AM colonisation
costs would therefore compete with plant growth for available C reserves. The aims of
this study were to assess the host C economy during AM development and the subsequent
C-costs of N and P uptake, as well as the effects of C costs on host growth. This was
evaluated in two separate experiments; one assessing the symbiotic influence on the C
costs of fungal establishment and nutritional benefits, whilst the other one evaluated the
effects of the symbiosis on host growth and nutrient productivities.
This study has shown that AM acts as a C sink, competing with the host for available C.
Past work on the AM sink effect has focused mainly on the movement of photosynthetic
C below ground to support the AM fungus. This however, does not take into account the
effect that stored C will have on the C economy of the plant and symbiosis. The role of
stored C becomes even more crucial when working with deciduous plants that rely on
stored C for new growth at start of a growing season. It has been reported that stored C in
AM plants is remobilized at the start of a growing season and then the C reserves are
refilled towards the end of the season, when the plants enter dormancy.
The initial costs of AM fungal colonisation were borne by the above-ground C reserves,
at the expense of new growth in host plants. These costs were offset once the plateau
phase was reached, and the depleted reserves started to refill. Once established, the active
symbiosis imposed a considerable below ground C sink on host reserves. In spite of these costs, the improved P nutrition of AM roots was achieved with a more efficient C-use.
This concurs with other findings, that of the belowground C allocated to AM roots, a
greater part is used by AM respiration and a smaller part for P uptake. The C costs of the
AM fungal phase of rapid development can be seen as negative to root growth and shoot
development. These negative effects may continue for a period of time, even during the
plateau phase of fungal development. Once the AM symbiosis is fully established, the
host growth and development is then improved to a greater extent than in non-AM plants.
From this study it can be concluded that AM growth directly competes with host
development, but the symbionts revert to a beneficial partnership once it is fully
established. / AFRIKAANSE OPSOMMING: Die C koste van arbuskulêre mikorisa (AM) in wingerdstokke is ondersoek. Beide
rustende wingerdstokke en AM koloniseering is afhanklik van gestoorde C vir
aanvanklike groei. AM kolonisering sou dus met plantgroei kompeteer vir
beskikbare C reserwes. Die doelstellings van hierdie ondersoek was eerstens om
die C-ekonomie van die gasheer tydens AM ontwikkeling en die gevolglike Ckostes
van N en P opname te bepaal en tweedens sowel as die invloed van C
veranderings op gasheergroei vas te stel. Hierdie is in twee afsonderlike
eksperimente ondersoek: een om die simbiotiese invloed op die C-kostes van
swam-vestiging en voedingsvoordele te bepaal, terwyl die ander die uitwerking
van simbiose op gasheergroei en voedings doeltreffenheid evalueer het.
Die ondersoek het bewys dat AM, as ‘n C-sink, kompeteer met die gasheer vir
beskikbare C. Vorige werk oor die AM sink-effek het hoofsaaklik gefokus op die
afwaartse beweging van fotosintetiese C om die AM-swam ondergronds te
ondersteun. Die werk neem egter nie in ag wat die effek van gestoorde C op die
C-ekonomie van die plant en simbiose sou wees nie. Die rol van gestoorde C is
selfs nog meer belangrik wanneer met bladwisselende plante gewerk word, omdat
sulke plante op gestoorde-C vir nuwe groei aan die begin van die groeiseisoen
staatmaak. Dit is op rekord dat gestoorde C in bladwisselende plante by aanvang
van die groeiseisoen gemobiliseer word en dat die C-reserwes teen die einde van
die seisoen wanneer die plante rustyd nader, weer hervul word. Die aanvanklike kostes van AM kolonisering is deur die bogronds C-reserwes, ten
koste van nuwe groei van die gasheerplante, gedra. Hierdie kostes herstel sodra
die plato-fase bereik is, waar die uitgeputte reserwes begin hervul het.
As die aktiewe simbiose eers gevestig is, sal dit as ‘n onderg P-voeding van AM
wortels verkry wordrondse C-sink vir gasheer optree.Hierdie C verbruik word
egter as doeltreffend beskou aangesien verbeterde. Dit is bekend dat ‘n groter deel
van die ondergrondse C geallokeer word aan AM-wortels, deur middel van AM
respirasie en P-opname. Die C-kostes van die AM-fungus tydens die fase van
vinnige ontwikkeling, kan ‘n negatiewe effek op wortel- en lootontwikkeling hê.
Hierdie negatiewe uitwerking kan vir ‘n tydperk voortdeur, selfs gedurende die
plato-fase van fungi-ontwikkeling. Sodra die AM-simbiose volledig gevestig is,
word gasheergroei en ontwikkeling tot ‘n groter mate verbeter as in plante sonder
AM-fungi. Hierdie ondersoek het bewys dat AM groei direk met
gasheerontwikkeling kompeteer, maar dat die simbiose ‘n voordelige vennootskap
vorm sodra dit volledig gevestig is.
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