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Title: A role for differential host resistance to the hemiparasitic angiosperm, Rhinanthus minor L. in determining the structure of host plant communities
Author: Cameron, Duncan Drummond
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2004
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This study describes the effect of the root hemi-parasitic angiosperm Rhinanthus minor on the structure of the communities in which it lives and seeks to elucidate a mechanism through which the parasite acts to effect these changes in the community. Field manipulations revealed that R. minor suppressed the growth of grasses and legumes in a newly sown meadow whilst promoting the forbs within one growing season.  In contrast the removal of R. minor from mature meadow plots did not influence their composition.  After an additional growing season the parasite did not further influence the composition of the new meadows but removal did begin to benefit the biomass of mature plots. In isolation the parasite caused most damage to grasses whilst leaving legumes and forbs undamaged.  Moreover, the parasitic performed worst in terms of growth and photosynthesis when attached to the forbs.  Consequently the parasite was able to moderate intra-specific competition between grasses and forbs.  I thus hypothesised that forbs were able to prevent the parasite from abstracting resources where as grasses could not. Tracer experiments using isotopically (15N) labelled potassium nitrate confirmed this hypothesis showing that more of the resources taken up by the host were stolen by the parasite from grasses than from forbs.  There were much variability in the translocation of resources from the legume studied. The reasons underlying the differential uptake of resources were highlighted using histological studies which showed that all of the forbs possessed successful resistance mechanisms to the parasite whilst no successful resistance was observed in the grasses or legumes.  Two different resistance mechanisms were observed in the forbs; hypersensitive cell-death at the host-parasite interface and host lignification.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available