Host provenance effects on germination and establishment of two New Zealand mistletoes (Loranthaceae)

Abstract

1. The influence of host genotypes (provenances) on mistletoe establishment, or the susceptibility of different host provenances to mistletoe infection, has not previously been documented. 2. We quantified the germination and establishment of two New Zealand mistletoes [Alepis flavida (Hook. f.) Tiegh. and Peraxilla tetrapetala (L. f.) Tiegh.] on different provenances of their main host Nothofagus solandri (Hook. f.) Oerst. in a 'common garden' host experiment. 3. Germination was high for both species (96.9% for A. flavida and 97.4% for P. tetrapetala), but establishment was much lower (13.2 and 2.3%, respectively). 4. Deviance explained in statistical models of germination with respect to light, branch growth rate, host tree provenance and tree effects was lower than that explained in models of establishment (20.3 compared with 33.2% for A. flavida; 35-9 compared with 73.7% for P. tetrapetala). 5. While branch growth rate and host tree provenance were significant variables in the P. tetrapetala establishment model, the most significant effect for both species was due to individual trees within provenances (24.9 and 42.8% of total deviance, respectively, for A. flavida and P. tetrapetala). 6. Even when a range of factors are accounted for (including branch growth rate and host tree provenance), there is still a large degree of unpredictability in mistletoe establishment that reflects either inherent or environmental conditions associated with individual trees.