Interactions between the root hemiparasitic plant Rhinanthus alectorolophus and its hosts

Parasitic plants attach to the shoots or roots of other plants with a specialized organ called haustorium and extract water, carbon and other nutrients from the host. Annual, herbaceous root hemiparasites are typically generalists which grow in species-rich communities and can interact with a wide range of host species, but the outcome of the interaction between root hemiparasites and their hosts varies greatly depending on the identity of the host species. In this thesis, I studied several factors which could affect parasite-host interactions. As model species I used Rhinanthus alectorolophus, an annual root hemiparasite found in central European grasslands which mostly interacts with perennial plant species. I addressed the following specific questions: (i) Are parasite-host interactions affected by the genotype of the parasite? (ii) How does host age at the time of infection affect parasite-host interactions? (iii) How strong is the variation in the quality of legume species as hosts for R. alectorolophus, and which host traits most strongly affect parasite-host interactions?