Prefertilization barriers between different Bromeliaceae

Pollen germination on stigma, pollen tube growth in the style and pollen tube penetration of ovules have been studied of excised pistils, after crossing and selfing of 7 bromeliad species. Prefertilization barriers were observed after intraspecific, interspecific and intergeneric crosses. Satisfactory pollen germination in both selfed and crossed flowers showed that the stigma did not act as a barrier. Self-incompatibility in Aechmea B and Tillandsia A was confined in the style, which is characteristic for the gametophytic SI system. Unilateral incongruity between Aechmea A and Aechmea B was not related to self-incompatibility, but could be explained by differences in style length. Incompatibility, interspecific and intergeneric incongruity were different with respect to the number of pollen tubes in the style, ratio of pollen tube length and style length, and the number of pollen tube abnormalities. The prefertilization barriers of intergeneric crosses between different subfamilies were not greater than these observed within a subfamily.