Open Access

Briony Cadzow, Susan M. Carthew

• Experimental hand pollinations were used to examine factors that influence fruit production in Persoonia juniperina (Proteaceae). Assessment of the breeding system indicated no clear pre-zygotic barriers to self-fertilisation. Rates of pollen tube growth and numbers of pollen tubes were similar after selfing and outcrossing. Plants also clearly had the capacity to produce fruit from selfing, although there was some evidence of inhibition in the development of selfed zygotes. More fruit were initiated after cross-pollination, and rates of abortion were greater after selfing, resulting in lower final fruit set. Inhibition of selfed fruit is most probably exhibited post-zygotically since the percentage of ovules penetrated did not differ between treatments. However, at this stage it is difficult to differentiate between late-acting self-incompatibility and genetic load. Supplementary hand pollinations did not increase numbers of pollen tubes or percentage fruit set above natural levels, indicating that plants in the population were not pollen limited. These results contrast with those found in most other species of Proteaceae.