View/Open - ResearchSpace - University of KwaZulu-Natal
View/Open - ResearchSpace - University of KwaZulu-Natal
View/Open - ResearchSpace - University of KwaZulu-Natal
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Abstract<br />
Romulea is a genus with numerous attractive and endangered species with<br />
horticultural potential. This genus in the Iridaceae has its centre <strong>of</strong> diversity in the<br />
winter-rainfall zone <strong>of</strong> South Africa. This thesis uses ecophysiological and<br />
biotechnological techniques to investigate the physiology behind the propagation <strong>of</strong><br />
some species in this genus.<br />
The ecophysiological techniques <strong>of</strong> soil sampling and analysis and germination<br />
physiology were used to determine the natural and ex vitro growth and development<br />
requirements <strong>of</strong> these plants, while biotechnological techniques are used to<br />
determine the in vitro growth and development requirements <strong>of</strong> these plants and to<br />
increase the rate <strong>of</strong> multiplication and development.<br />
Soil sampling and analysis revealed that R. monadelpha and R. sabulosa, two <strong>of</strong> the<br />
most attractive species in the genus, grow in nutrient poor 1:1 mixture <strong>of</strong> clay and<br />
sandy loam soil with an N:P:K ratio <strong>of</strong> 1.000:0.017:0.189 with abundant calcium.<br />
To investigate the physical properties <strong>of</strong> the seeds, imbibition rate, moisture content<br />
and viability <strong>of</strong> seeds were determined. The seed coat and micropylar regions were<br />
examined using scanning electron microscopy. To test for suitable stimuli for<br />
germination, the effect <strong>of</strong> temperature and light, cold and warm stratification, acid and<br />
sand paper scarification, plant growth promoting substances, deficiency <strong>of</strong> nitrogen,<br />
phosphorous and potassium, and different light spectra (phytochromes) on<br />
germination were examined. An initial germination experiment showed germination<br />
above 65% for R. diversiformis, R. leipoldtii, R. minutiflora and R. flava seeds placed<br />
at 15°C; while seeds <strong>of</strong> other species placed at 15°C all had germination<br />
percentages lower than 30%. More extensive germination experiments revealed that<br />
R. diversiformis and R. rosea seed germinate best at 10°C, R. flava seed germinates<br />
best when cold stratified (5°C) for 21 days and R. monadelpha germinates best at<br />
15°C in the dark. Seeds <strong>of</strong> R. diversiformis, R. flava, R. leipoldtii, R. minutiflora, R.<br />
monadelpha and R. sabulosa seem to all exhibit non-deep endogenous<br />
morphophysiological dormancy while seeds <strong>of</strong> R. camerooniana and R. rosea appear<br />
to have deep endogenous morphophysiological dormancy.<br />
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