Browsing by Author "Poole, Caroline Jacqueline"

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    Growth and nutrition of Bruniaceae
    (Stellenbosch : Stellenbosch University, 1999-12) Poole, Caroline Jacqueline; Jacobs, G.; Saayman, D.; Stellenbosch University. Faculty of AgriSciences. Dept. of Horticultural Science.
    ENGLISH SUMMARY: Bruniaceae are increasingly being harvested commercially as cut flowers in South Africa for the European cut flower markets. The need to cultivate certain species requires research to develop economically viable cultivation methods and the selection of productive cultivars. This study deals with horticultural and nutritional aspects of Bruniaceae, particularly Brunia albiflora (Pillans). Flower initiation and development of two species of Bruniaceae, Brunia albit/ora and Berzelia galpinii (Pillans) were investigated to determine when floral initiation occurred and to qualify progression of flower differentiation and development. It was observeq that development was six months apart with Brunia albiflora initiating florets in October and Berzelia galpinii in May. Carbohydrate studies were also carried out over a one year period, to determine seasonal changes of carbohydrates which would enable manipulation of cultural practices for increased yield. It was observed that new shoots had lower carbohydrate contents compared to flowering shoots. Side shoots of flowering shoots had higher starch and sugar content than main shoots after winter. The starch content decreased in side shoots following flower initiation in October, with the total sugar content of side shoots showing the same pattern. It appeared that side shoots were net carbohydrate sources and exported assimilates to the developing inflorescence. The increase in carbohydrates of the inflorescence was higher than the loss in the side shoots and it seems that Brunia albiflora is mainly reliant on current photosynthates for their growth. Soil and plant nutrient requirements of Brunia albiflora were investigated by selecting three localities in the Western Cape. Variation in terms of growth performance was large at each locality, presumably because of different soil types. Calcium in topsoils showed a significant negative correlation with plant performance, whereas higher exchangeable Na correlated with good plant performance. Soils with high clay-content seem to be unsuitable for Brunia albiflora possibly due to poor aeration. Positive correlations with plant performance were also found for organic carbon, N, P and K, as well as exchangeable acidity and exchange capacity of the B horizon. Leaf and stems were sampled at two dates to determine which component and time of sampling best reflected the nutrient status of the plant. Leaves were decided on as index tissues and sampling at anthesis (February) was appropriate. Leaf nutrient concentrations of Brunia albiflora were found to be low in N, P, K, Mg and Zn compared to other woody plant, whereas Ca, Cu and Mn appeared to have similar concentrations. The removal of macro-elements by cropping a plantation in full production was calculated as 38 kg N, 1.5 kg P, 35 kg K, 40 kg Ca and 5 kg Mg per hectare based on 25 flowering stems per plant and 5 000 plants per hectare. These results can be used as a basis for fertiliser recommendations, pending the results of fertiliser trials. As the demand for these flowers increases, there will be a greater demand for better quality. Improved production and flower quality should compensate for the extra costs of fertilisers.