Evaluation of best practices for local chicory production.
Manyoni, Nonduduzo Nelly.
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Chicory roots obtained from Cichorium intybus are commonly used to produce a caffeine-free coffee substitute. Although the crop has been produced in South Africa for many decades, the country still relies on imported chicory roots to meet its chicory needs, as satisfactory yields are often not achieved. The low yields are associated with the use of poor quality seed, which often results in poor crop establishment. In addition, there are limited options for weed control in chicory since only one herbicide is currently registered for use with chicory in South Africa. Chicory seeds vary in seed coat colour and research has indicated that seed coat colour maybe associated with seed quality of chicory. Results by various authors showed dark chicory seeds to have better performance than light coloured seeds however, contrary findings showing poor performance of dark coloured seeds compared to light coloured seeds have also been reported. There is a need to gain a deeper understanding of the possible association between seed coat colour variation and seed performance in chicory so as to come up with best management practises in order to obtain maximum crop establishment and optimum yields. The aim of the study was to evaluate the use of the image analysis in determining seed coat colour differences in chicory and to gain a deeper understanding of possible associations between seed coat colour variation and seed quality with respect to germination and vigour. In addition, the study assessed the effect of seed coat colour on germination, seedling growth and development of chicory in response to different priming solutions and durations. Lastly, a field experiment was conducted to identify the optimal planting density of chicory with respect to seed coat colour and weed management strategies. Seeds (cv. Orchies) were obtained from Nestle®, KwaZulu-Natal. In the first experiment (chapter three) seeds were separated visually into eight seed colours and then separated and assigned to a certain group using an image analysis system. This analysis system indicated that two colour categories could be separated with respect to hue. These groups were categorized as light and dark coloured seeds. Results also showed significant interactions (P < 0.05) between seed colour and seed quality test with respect to germination percentage and mean germination time. There were highly significant interactions (P < 0.001) between seed coat colour and seed quality test as detected by the germination velocity index (GVI) and imbibition time. Electrolyte leakage from the seeds was not significantly different (P > 0.05) between the seed colour groups. Results from chapter four showed osmo- and hydro-priming to improve seed quality of chicory through improvements in germination velocity index (GVI) and mean germination time (MGT). Osmo-priming resulted in relatively high improvements in seed quality compared with hydro-priming. Priming improved seedling establishment (mean emergence time (MET), seedling length, shoot length, root length, fresh mass and, root/ shoot ratio). Results from the field trial showed the interaction of planting density, seed coat colour, and weeding method to be significant for total plot yield. This suggested that, no optimal crop stand exists with regards to weeding methods and seed coat colour. On the other hand, if the agronomic parameter of interest is biomass plot yield, the optimal plant density would be 200 000 plants ha-1. Herbicide application tended to reduce agronomic performance of dark coloured seeds.