Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: An open air hydroponic production system (OHS) is based on classic hydroponic
principles, with the difference that it lacks climatological control because the plants are
not produced in greenhouses and are cultivated in the outside environment. In these
systems the plant is provided with all the essential nutrients through the irrigation
system, which is scheduled according to accurate measurements of the available soil
water, in three to seven pulses a day. The rationale is that, by delivering nutrients each
day, the mixes can be representative of what the plant actually requires for that specific
phenological stage.
The aim of this study was to monitor the usefulness and impact of OHS on table
grape production within the framework of a case study. For this purpose, it was
necessary that all factors involved in the development and growth of the plant should be
studied and integrated in a multidisciplinary approach. Currently very limited information
exists on basic guidelines for the effective implementation of these systems for table
grape production, particularly with regard to local conditions. As a start, and to establish
some guidelines and measurable parameters for the implementation of these systems,
vegetative growth parameters were analysed within the framework of yield and fruit
quality. The experiments were performed in a commercial vineyard in the Paarl region
and the cultivars used were Dan ben Hannah (DBH) and Waltham Cross (WC).
Relevant soil and climatic conditions, irrigation scheduling, fertiliser application, as well
as cultivation practices, were taken into account. The soil maps provided information on
the soil types identified in the blocks prior to the establishment of the two cultivars. The
conventionally treated vines were irrigated and fertilised according to historical block
data, and the OHS-treated vines according to programmes established by two different
consultants.
The experimental layout included a comparison of conventional cultivation methods
and vines that had been switched over from conventional methods to OHS in the middle
of 2000. All measurements within the different treatments were done at specific
measuring points laid out statistically. Ten phenological stages were chosen to monitor
the various aspects throughout the season for both cultivars treated conventionally and
hydroponically. All relevant climatic parameters were collected for this specific
production unit. The growth, fertility and quality indicators of these cultivars under the
mentioned cultivation practices are discussed and established through quantitative
analysis
One of the aims, namely to show that established table grape vines could adapt
from micro-irrigation to drip irrigation within two seasons in terms of root adaptation, was
proven in this study. Initially the soil types were identified as Cartref, Clovellyand
Glenrosa for both cultivars. The WC block contained an Avalon and the DBH a
Westleigh soil type as well. The soil pits in all four treatments revealed the soil type to
be a Tukulu form with differences in the clay content. Active roots developed
underneath the drip lines for the OHS-treated cultivars, while the roots were still evenly distributed over the entire soil profile for the conventionally treated vines. Also, both
cultivars adapted to OHS in terms of yield and production within two seasons, especially
WC, which produced a higher yield in the 2001/2002 season than in the previous four
seasons.
DBH showed a strong vegetative reaction to OHS in terms of excessive vegetative
growth, which had an indirect effect on fruit quality and bud fertility. A higher rate of bud
mite infection in the OHS-treated vines also had a negative influence on bud fertility.
The excessive vegetative growth was due to a rainy 2001/2002 growth season, in
combination with the irrigation and fertiliser programmes. The irrigation and fertiliser
programmes were changed from the 2000/2001 to the 2001/2002 season because of
the change in consultants. As a result of this change, the OHS-treated vines were given
very high nitrogen, phosphorus, potassium and micronutrient applications in the
2001/2002 season. The penetration of light in the canopy of the OHS-treated DBH was
lower than in the conventionally treated DBH as a result of the above-mentioned factors,
but the situation in Waltham Cross was the opposite. In the winter season of 2001, both
OHS-treated cultivars were not fully adapted to the new system, as their pruning mass
was lower than in the conventionally treated cultivars. No significant differences were
determined for the winter cane starch content of both cultivars under conventional and
OHS treatments.
Effective fertiliser uptake proved to be suboptimal, especially in the case of calcium.
Fruit analyses showed a lower calcium content in the OHS-treated fruit, which led to a
poor skin cell structure and higher Botrytis infection during cold storage. The OHStreated
cultivars showed more compact bunches, with an overall smaller rachis
structure, which was another reason for the higher Botrytis infection during cold storage.
However, the more compact rachis structure could not be explained on the basis of the
elemental analyses. The OHS-treated DBH showed a more intense red berry colour,
while the OHS-treated WC had a higher Fosscan Brix value. Both OHS-treated cultivars
therefore ripened earlier than the conventional treatments.
One of the advantages of the use of OHS in table grape production shown in this
study was the ability to manipulate the phenology of the grapevine to provide fully
ripened grapes a few days earlier than the conventionally treated grapes. This kind of
advantage could be used to manipulate the production of table grapes for a better
market window.
Despite its limitations, this study concluded that the use of OHS for table grape
production might be a useful tool for future production management, but that accurate
management regarding irrigation and nutrient applications is a prerequisite. This will
have to be developed systematically through experimentation to fully unlock the
potential of the OHS management system for table grape production. This study
provides a starting point for future research to elucidate these aspects and has clearly
shown that even established vineyards can be switched to OHS in a relatively short
period of time. It is envisaged that the advantages of this system, as long as the correct
management protocols are in place, could have a positive effect on the production of
high quality fruit for the international market. / AFRIKAANSE OPSOMMING: 'n Oop hidroponiese produksiestelsel (OHS) is gebaseer op klassieke hidroponiese
beginsels, met die verskil dat OHS nie klimatologies beheer kan word nie. Die plante
word nie in glashuise of tonnelsisteme verbou nie, maar wei onder buitelug toestande.
Binne hierdie sisteme word die plante van alle noodsaaklike voedingstowwe deur die
besproeiingstelsel voorsien. Hierdie voedingstowwe word in drie tot sewe pulse per dag
volgens akkurate beskikbare grondwaterbepalings geskeduleer. Die rasionaal is dat,
deur die daaglikse lewering van voedingstowwe, die mengsels verteenwoordigend is
van die plant se behoefte vir 'n spesifieke fenologiese stadium.
Die doel van die studie was om die bruikbaarheid en impak van OHS op
tafeldruifproduksie binne die raamwerk van 'n gevallestudie te monitor. Alle faktore wat
by die groei en ontwikkeling van die plant betrokke is, moet in 'n multidissiplinêre
benadering bestudeer en geïntegreer word. Daar is tans slegs beperkte inligting oor die
basiese riglyne en effektiewe implementering van dié sisteme vir tafeldruifproduksie wat
spesifiek is vir plaaslike toestande. As 'n beginpunt, en om sekere riglyne en meetbare
parameters vir die implementering van die sisteme te vestig, is vegetatiewe parameters
binne die raamwerk van opbrengs en vrugkwaliteit geanaliseer. Alle eksperimente is in
kommersiële wingerdblokke in die Paarl-omgewing uitgevoer. Die kultivars wat vir die
studie gebruik is, is Dan ben Hannah (DBH) en Waltham Cross (WC). Alle relevante
grond- en klimaatstoestande, sowel as besproeiingskedulering, bemestingprogramme
en verbouingspraktyke is vir die projek in ag geneem. Ou grondkaarte het inligting ten
opsigte van die verskillende grondtipes wat voor die vestiging van die verskillende
kultivars geïdentifiseer is, verskaf. Die wingerde, onder konvensionele behandeling, is
volgens historiese blokdata besproei en bemes, terwyl die wingerde onder OHS volgens
geskeduleerde programme wat vanaf konsultante verkry is, besproei en bemes is.
Die eksperimentele uitleg het 'n vergelyking van konvensionele verbouingsmetodes
en wingerde wat in die middel van 2000 van konvensionele na OHS-verbouing
oorgeskakel is, ingesluit. Alle metings en analises binne die verskillende behandelings
het by spesifieke statistiesbepaalde punte plaasgevind. Tien fenologiese stadia is
gekies om die verskillende aspekte vir beide kultivars onder konvensionele en OHSbehandeling
gedurende die seisoen te monitor. Alle relevante klimaatsdata is vir die
spesifieke produksie-eenheid aangevra. Alle groei-, vrugbaarheids- en
kwaliteitsparameters van die kultivars onder die bogenoemde behandelingsmetodes is
bespreek en gevolglik deur kwantitatiewe analises bepaal.
Een van die doelwitte, naamlik om uit te vind of reeds gevestigde ouer wingerde in
terme van wortelaanpassing binne twee seisoene kan aanpas van mikrobesproeiing na
drup OHS, is deur die studie bevestig. Aanvanklik was die grondtipes geidentifiseer as
die vorme, Cartref, Clovelly en Glenrosa vir beide kultivars, met 'n Avalon vorm
adisioneel by WC, en 'n Westleigh vorm by die DBH. Grondprofiele het egter getoon dat
die grondtipes vir al vier behandelings 'n Tukulu vorm is met verskillende klei inhoude.
Aktiewe wortels het vir die OHS-behandelde wingerde onder die druppers ontwikkel,
terwyl die wortels in die konvensionele behandeling steeds eweredig oor die hele
grondprofiel versprei was. Beide kultivars het ook in terme van opbrengs en produksie binne twee seisoene ná die oorskakeling van die konvensionele behandeling na OHS
aangepas. WC het in die 2001/2002 seisoen 'n hoër opbrengs gelewer as in die vorige
vier seisoene.
Afgesien van die goeie aanpasbaarheid, het DBH 'n sterk vegetatiewe groeireaksie
ten opsigte van die OHS-behandeling getoon, wat 'n indirekte effek op vrugkwaliteit en
oogvrugbaarheid geopenbaar het. 'n Hoër mate van knopmiet infeksie in die OHSbehandelde
stokke kon ook 'n negatiewe bydrae tot oogvrugbaarheid gemaak het. Die
sterk vegetatiewe groei kon aan die hoër reënval gedurende die 200112002
groeiseisoen, tesame met die besproeiings- en bemestingsprogramme, toegeskryf
word. Die besproeiings- en bemestingsprogramme is verander van die 2000/2001
seisoen na die 2001/2002 seisoen weens die aanstelling van 'n ander konsultant. As
gevolg van hierdie verandering het die OHS-behandelde stokke baie hoë toedienings
van stikstof, fosfaat, kalium en mikroelemente in die 2001/2002 seisoen ontvang.
Sonligpenetrasie in die wingerdlower van die OHS-behandelde DBH was laer as in die
konvensionele behandeling as gevolg van die bogenoemde faktore. Die situasie vir WC
was egter die teenoorgestelde. Tydens die winterseisoen van 2001 was beide
oorgeskakelde kultivars nie ten volle by die nuwe OHS-behandeling aangepas nie, soos
gesien kan word in die laer lootmassas in vergelyking met die konvensionele kultivars.
Geen beduidende verskil is vir die hoeveelheid stysel in die winterlote van beide
kultivars onder konvensionele en OHS-behandeling verkry nie.
Effektiewe voedingstofopname was suboptimaal, veral betreffende kalsium.
Vruganalises het 'n laer kalsiuminhoud in die OHS-behandelde druiwe getoon, wat
aanleiding gegee het tot 'n swakker seistruktuur in die druiwedoppe en 'n hoor mate van
Bottytis-infeksie gedurende koelopberging. Die OHS-behandelde kultivars het meer
kompakte trosse getoon met kleiner trosraamwerke, wat ook aanleiding kon gegee het
tot 'n hoër Botrytis-infeksie. Die kleiner trosraamwerke kon nie deur voedingstofanalises
verklaar word nie. Die OHS-behandelde DBH het 'n hoër kleurintensiteit getoon, en die
OHS-behandelde WC het 'n hoër suikerinhoud getoon ten opsigte van die
konvensionele behandeling. Beide OHS-behandelde kultivars was dus vroeër ryp as die
konvensionele behandelings.
Een van die voordele van OHS wat uit die studie voortspruit, is die vermoë om
wingerdfenologie te manipuleer om ryper druiwe vroeër in die seisoen te verkry. Hierdie
tipe voordeel kan aangewend word om druiwe vir "n beter markvenster te produseer.
Hierdie studie, tesame met al sy beperkinge, kom tot die gevolgtrekking dat die
gebruik van OHS vir tafeldruifproduksie 'n nuttige instrument vir toekomstige
produksiebestuur is, maar dat die optimale bestuur van besproeiing en bemesting as
kritiese faktore beskou moet word. Hierdie faktore sal sistematies deur intensiewe
navorsing ontwikkel moet word om die volle potensiaal van OHS te ontsluit, spesifiek vir
tafeldruifproduksie. Hierdie studie kan as 'n beginpunt gebruik word vir toekomstige
navorsing vir meer toegeligte verklarings van die bogenoemde aspekte, veral met die
voordeel dat reeds gevestigde wingerde maklik en vinnig by OHS kan aanpas. Die
voordele van OHS kan 'n groot positiewe invloed op die produksie van hoër kwaliteit tafeldruiwe vir die internasionale mark hê, mits die regte bestuursriglyne in plek is en
toegepas word.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/49775 |
| Date | 12 1900 |
| Creators | Van Zyl, Sonet |
| Contributors | Vivier, M. A., Stassen, P. J. C., Stellenbosch University. Faculty of AgriSciences. Dept. of Horticulture. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 148 p. : ill. |
| Rights | Stellenbosch University |
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