Thesis (DPhilAgric)--Stellenbosch University, 2002 / ENGLISH ABSTRACT: South Africa is one of the worlds leading producers of chicory (Cichorium intybus L.). Most of
the chicory produced is used locally for the production of instant coffee. Witloof chicory, or
Belgian endive, however, is a vegetable crop grown from the root of Cichorium intybus L. var.
foliosum. This is done by placing the mature taproot in a controlled, dark environment after
vernalization and supplying it with water and nutrients by means of hydroponics. Witloof chicory
is new to the South African market and is only produced on a limited scale. Nonetheless, seeing
that chicory is successfully grown on a large scale for the coffee industry it seemed reasonable to
investigate the cultivation of this essentially unknown vegetable locally.
The focus of this study was on the evaluation of new witloof production techniques during the
second stage of witloof (chicon) cultivation, also called 'forcing'. To this end, locally grown
witloof chicory roots were used in all trials. In order to establish the effects of several irrigation
methods on lateral root formation and chicon quality, witloof chicory roots were forced using the
conventional means of hydroponic irrigation as well as ebb-and-flood and aeroponic irrigation.
Lateral root formation was significantly increased when either ebb-and-flood or aeroponic
irrigation was applied compared to that obtained with the conventional method. This increase in
lateral root formation was, however, to the detriment of chicon quality (QI), possibly as a result of
competition for limited carbohydrate reserves.
In an attempt to optimize the aeroponic irrigation method, roots were forced in non-vertical
positions. Placing roots horizontally during forcing resulted in a significantly lower marketable
chicon yield than where roots were placed vertically. The loss in yield was probably brought
about by an increased fallout percentage rather than by a decrease in chicon production.
Considering the pivotal role that sucrose plays in the development of the chicory head, sucrose
was applied exogenously to the root before and/or during forcing. Dry matter chicon yield was negatively effected by exogenously applied sucrose. This could have been due to an increased
incidence of fungal or bacterial infections or causative of roots absorbing less water resulting in
the inability of the plant to utilize the applied sucrose during chicon development.
Fungal and bacterial infections are known to have a detrimental effect on witloof chicory
production. An environmentally friendly product for disease control, 'Desogerme SP®', was used
to contain or reduce infection. Irrigation of roots with 'Desogerme SP®' containing nutrient
solution increased chicon yield by 31%.
From this study it became clear that some new production techniques applied had the potential of
improving lateral root formation or quality during growth. However, the conventional way of
irrigation remains the most effective compared to the other techniques applied, but could possibly
be improved to some extent by incorporating 'Desogerme SP®' either as a pretreatment or in the
nutrient solution.
A breakthrough was made with the development of the quality index (QI). The ongoing limitation
of statistically analyzing quality data of chicons sorted according to quality-classes was overcome
by making use of this tool. Despite the fact that the index was developed specifically for use on
witloof, it is has the potential of being applied to quality data of a wide variety of crops. / AFRIKAANSE OPSOMMING: Suid Afrika is een van die wêreld se grootste produsente van sigorei (Cichorium intybus L.). Die
meeste plaaslik geproduseerde sigorei word vir die produksie van kitskoffie benut. Witloofsigorei,
of Belgiese "endive", is egter 'n groentegewas wat vanaf die wortel van Cichorium
intybus L. var. foliosum gekweek word. Dit word gedoen deur die volwasse penwortel na
vemalisasie in 'n gekontroleerde, donker omgewing te plaas en met 'n hidrokultuurstelsel van
water en voedingselemente te voorsien. Witloof is nuut op die Suid Afrikanse mark en word net
op beperkte skaal geproduseer. Aangesien sigorei suksesvolop groot skaal vir die koffieindustrie
geproduseer word, blyk dit logies om die moontlikhede te ondersoek om hierdie relatief
onbekende groente plaaslik te kweek.
Die fokus van hierdie studie was gerig op die evaluasie van nuwe produksietegnieke gedurende
die tweede fase van witloofproduksie, wat ook as forsering bekend is. Plaaslik gekweekte witloof
sigoreiwortels is vir alle eksperimente gebruik. Die invloed van 'n verskeidenheid
besproeiingsmetodes is op sywortelproduksie en witloof krop-kwaliteit ondersoek. Witloofwortels
is geforseer deur van 'n konvensionele hidrokultuur-stelsel gebruik te maak wat met 'n
ebb-en-vloed en 'n lugsproei sisteem vergelyk is. Sywortel-produksie was betekenisvol hoër waar
ebb-en-vloed of lugsproei sisteme toegepas is. Hierdie verbetering in sywortel-ontwikkeling was
egter tot nadeel van krop-kwaliteit, vermoedelik as gevolg van die allokasie van koolhidrate na
sywortels, eerder as na die groeipunt.
In 'n poging om die lugsproei besproeiingsmetode te verbeter en om swamsiektes te verminder, is
wortels in nie-vertikale posisies geforseer. Wortels wat gedurende forsering horisontaal ingetafel
was, het 'n betekenisvol laer opbrengs van bemarkbare kroppe getoon as wortels wat vertikaal
geplaas was. Die verlies aan opbrengs kon toegeskryf word aan 'n verhoging van afval, aangesien
geen betekenisvolle afname in vars krop-gewig gevind is nie. Aangesien sukrose 'n belangrike rol in die ontwikkeling van die witloofkrop speel, is sukrose voor
en tydens forsering aan die wortels toegedien. Droë materiaal krop-opbrengs is negatief deur die
toediening van sukrose beïnvloed. Dit kon moontlik as gevolg van 'n verhoogde voorkoms van
swam- of bakteriese infeksies gewees het of 'n aanduiding wees dat behandelde wortels minder
water geabsorbeer het en die toegediende sukrose nie kon gebruik gedurende krop-ontwikkeling
me.
Swam- en bakteriese infeksies is bekend vir hul negatiewe uitwerking op witloofproduksie. 'n
Omgewingsvriendelike middel, 'Desogerme SP®' is gebruik om siektes te beheer ofte verminder.
Wortels wat met 'n 'Desogerme SP®' bevattende voedingsoplossing besproei is, het 'n 31%
verhoging in krop-opbrengs getoon.
Uit data wat gedurende hierdie studie ingesamel is, blyk dit duidelik dat sommige van die nuwe
produksietegnieke wel die potensiaal het om sekere planteienskappe te verbeter. In geheel gesien
bly die konvensionele metode van besproeiing die mees effektiewe, wanneer dit vergelyk word
met die ander wat getoets is. Die konvensionele metode kan moontlik verbeter word as
'Desogerme SP®' as 'n vooraf-behandeling of as deel van die voedingsoplossing geïnkorporeer
word.
'n Deurbraak is met die ontwikkeling van 'n kwaliteitsindeks (QI) gemaak. Ernstige beperkings
word met statistiese ontledings van kwaliteitsdata ervaar waar kroppe volgens kwaliteitskiasse
gesorteer word. Hierdie probleme is met behulp van die QI oorkom. Ongeag die feit dat die
indeks spesifiek vir gebruik by witloof ontwikkel is, het dit die potensiaal om toepassing te vind
by 'n wye reeks landboukundige produkte.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/97547 |
| Date | 03 1900 |
| Creators | Konig, Roman |
| Contributors | Combrink, Nicolaas, Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 79 p. : ill. |
| Rights | Stellenbosch University |
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