Browsing by Author "Konig, Roman"

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    Witloof chicory (Cichorium intybus L. var. foliosum) as a vegetable crop in South Africa
    (Stellenbosch : Stellenbosch University, 1999-12) Konig, Roman; Combrink, N. J. J.; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    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.
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    Witloof chicory (Cichorium intybus L. var.foliosum) - evaluation of new forcing techniques
    (Stellenbosch : Stellenbosch University, 2002-03) Konig, Roman; Combrink, Nicolaas; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    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.