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Witloof chicory (Cichorium intybus L. var. foliosum) as a vegetable crop in South Africa

Konig, Roman (1999-12)

Thesis (M.Sc. Agic.) -- University of Stellenbosch, 1999.

Thesis

ENGLISH SUMMARY: Witloof chicory (Cichorium intybus L. var. foliosum) is a new vegetable crop to South Africa. It is a typical Belgian product and English literature on production of this crop is scarce. The first aim of this study is to compile a summary of relevant literature in the form of a manual for quick reference and practical use concerning chicon cultivation in hydroculture. Endogenous gibberellic acid (GA) is known to play a pivotal role in the vernalization process of plants requiring a cold induction for flowering. The second goal of this study is to clarify the effect that an exogenous GA application has on the vernalization process of chicory roots grown for witloof production. Five cultivars of witloof chicory (Cichorium intybus L.) were treated by applying GA as a leaf and a root treatment, each at a high and a low concentration. After forcing the treated roots, the chicons were evaluated according to international quality standardization. Chicon quality was then used as an arbitrary indicator for completed root-vernalization. Irrespective of concentration, the GA leaf treatment showed no significant difference in chicon quality when compared to no treatment. A GA root treatment, on the other hand, had a strong retarding effect on chicon quality, again irrespective of the hormone concentration applied. In a follow-up trial to which a cold treatment was added, no significant difference in chicon quality was found between GA treatments and a cold induction treatment. The control plants, however, produced significantly more high quality chicons when compared to those plants that received GA treatments. It was concluded that GA had no positive effect on advancing root-vernalization. Further investigation then showed that root-vernalization may already occur during the vegetative growth period on the field as a result of high irradiance and high temperatures. In this case exogenous GA application would have no further effect.

AFRIKAANSE OPSOMMING: Witloof sigorei (Cichorium intybus L. var. foliosum) is 'n nuwe groentesoort in SuidAfrika. Dit is 'n tipiese Belgiese produk. Engelse literatuur in verband met die produksie hiervan is skaars. Die eerste doelwit van hierdie studie is om 'n samevatting van relevante literatuur saam te stel wat kan dien as 'n handleiding vir die produksie van witloof in 'n waterkultuurstelsel. Dit is bekend dat endogene gibberelliensuur (GA) 'n beduidende rol speel in die vemalisasie van plante wat 'n koue periode benodig vir blominduksie. Die tweede doelwit van die studie was om die uitwerking van 'n GA toediening op die vemalisasie van sigorei wortels, wat geteel is vir witloof produksie, na te vors. Vyf kultivars van witloof sigorei (Cichorium intybus L.) is behandel deur GA toe te dien as 'n blaar- en wortelbehandeling, elk by 'n hoe en 'n lae konsentrasie. Nadat die behandelde wortels geforseer is, is die witloof koppe volgens intemasionale kwaliteitstandaarde ,geevalueer. Kopkwaliteit is daarna as 'n arbitrere indikator vir voltooide wortelvemalisasie gebruik. Die GA blaartoediening het by geeneen van die getoetse konsentrasies enige verskil in kopkwaliteit veroorsaak nie. 'n GA wortelbehandeling het egter die kopkwaliteit betekenisvol verlaag, weereens onafhanklik van die hormoon konsentrasie wat toegedien is. In 'n daaropvolgende eksperiment waar 'n koue behandeling bygevoeg is, is geen beduidende verskil gevind in kopkwaliteit as GA toedienings vergelyk word met 'n koue behandeling nie. Die kontrole plante het egter betekenisvol meer hoe kwaliteit koppe gevorm in vergelyking met die plante wat 'n GA behandeling ontvang het. Die gevolgtrekking is gemaak dat GA geen positiewe uitwerking gehad het op die bevordering van wortel vemalisasie nie. 'n Verdere ondersoek het getoon dat wortel vemalisasie al gedurende die vegetatiewe groeiperiode op die veld kan plaasvind as gevolg van hoe sonligintensiteit en hoe temperature. In sodanige gevalle sou 'n GA toediening geen verdere voordeel inhou nie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/51551
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