This thesis describes investigations which aim to increase understanding of the effect of temperature on root system development and longevity and to consider the role played by an important symbiotic fungus known as Arbuscular Mycorrhizae in influencing plant root demography. Mycorrhizal fungi (Order Glomales) are an important group of soil borne microorganisms which colonise the roots of most plants. The production and mortality of roots is an important factor determining nutrient and carbon fluxes in terrestrial ecosystems. The first experiment, carried out in soil and utilising <i>in-situ</i> camera techniques, minirhizotrons and image analysis software, establishes that in fact there is a temperature effect on root longevity, with roots living for shorter periods of time at higher temperatures. As this experiment was carried out in unsterile conditions the effect could have been due to a direct effect of temperature on the plant itself or due to other indirect effects such as the mineralisation of nutrients and fluctuating organic and inorganic N concentrations brought about by microbial activity. The remaining experiments utilise a microcosm system which was developed to enable visualisation of the whole root system <i>in situ</i>, whilst allowing definable levels of nutrients to be given to the plant. The system allows temporal and spatial root measurements to be made simultaneously and non-destructively. Results indicate that the altered longevity obtained in experiment one is not solely due to nutritional factors. Temperature has an impact on many aspects of root development including increased branching rates at higher temperatures, resulting in an increase in the number of higher order roots, as well as roots becoming longer and thinner with increasing temperature. These effects are likely to influence root longevity, as higher order roots are likely to survive for less time. AMF had the effect of increasing root:shoot ratios, thus, will also have implications in terms of nutrient cycling. In conclusion, understanding the dynamics of the plant root system is crucial to understanding ecosystem function, as temperature effects are significant, implications of climate change should be considered.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651002 |
| Date | January 1999 |
| Creators | Forbes, Paula J. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12026 |
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