Experiments were performed using a modification of the technique developed by Spanner and Prebble 1962 to monitor the translocation of tracers along the petiole of Nymohoides peltata. Three tracers were used, Br and Na and at least three experiments were performed using each isotope. A very complete record of tracer distribution in time and space was obtained for each isotope. Computer simulation of translocation was developed based on a physical model consisting of a centrally located conducting channel in which a mass flow occurs and a surrounding non-conducting ground tissue. Reversible lateral exchange takes place between these two. The simulation is characterised by an inputfunction and three dimensionless parameters, V, R and K which are related to the velocities of longitudinal flow and reversible lateral leakage and which can be varied with both time and distance. The simulation is possessed of considerable versatility and in this way has many advantages over existing mathematical models. The information it provides is useful in its own right and suggests that the importance accorded the linear nature of the semi-logarithmic profiles in the past is unwarrented. In association with the above simulation a simple direct search optimisation programme was developed based on the least squares criterion to match the simulation to the experimental data. It was found that an acceptable match to the experiments could only be obtained if the time course accumulation of activity in the root-stock was reduced by an arbitrary factor. Although this part of the work failed in its main objective of obtaining estimates of the translocation parameters, it at least suggested a way in which they may be estimated and is encouraging for future work.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:704230 |
| Date | January 1973 |
| Creators | Davidson, Harmon Robertson |
| Publisher | Royal Holloway, University of London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://repository.royalholloway.ac.uk/items/3c3ac7fd-0066-4171-901e-2e26f3a5cb7b/1/ |
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