In this thesis, the uptake kinetics of Cd by the liverwort D.
hirsuta and the moss A. androgynum were investigated. In
preliminary experiments, the toxicity of Cd to the bryophytes
was investigated by characterising the effects of Cd on
photosynthesis and K loss. Experiments were carried out to
explain the existence of variation between different
collections observed in uptake kinetics in the liverwort D.
hirsuta. Photosynthesis in D. hirsuta was more sensitive to Cd
than photosynthesis in A. androgynum. The sensitivity was
directly related to intracellular Cd concentrations. D. hirsuta
accumulated considerably higher concentration of intracellular
Cd than A. androgynum. Cd caused intracellular K loss in D.
hirsuta but not in A. androgynum.
Extracellular Cd uptake was rapid and independent of
metabolism. Intracellular Cd uptake as a function of Cd
concentrations followed Michael is-Menten kinetics.
Intracellular Cd uptake in D. hirsuta was affected by age of
the plant, K pretreatment and the site where plants were
collected. The moss A. androgynum displayed Cd uptake
acclimation when uptake was measured at low temperatures. The
results indicated that uptake kinetics could be affected by
seasonal variation.
Tolerance of Cd in the moss A. androgynum could be induced by pretreating the plants with low concentrations. The moss
possibly excludes Cd from the cytoplasm and thus reduces the
concentration of Cd in the cytoplasm to below toxic level. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10300 |
| Date | January 1997 |
| Creators | Mautsoe, Puseletso Jacinta. |
| Contributors | Beckett, Richard P. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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