ANALYSIS OF POLLEN-STYLE INTERACTIONS IN PETUNIA-HYBRIDA - THE DETERMINATION OF VARIANCE IN MALE REPRODUCTIVE SUCCESS

A factorial cross design was used to evaluate the influence of differe nces among pollen donors and recipients on variation in stylar attriti on of pollen tubes in self-fertile plants of Petunia hybrida. Pollinat ions to flower buds were used to reduce the inhibitory ability of the style and these crosses were compared with flower pollinations to asse ss the degree of stylar influence on pollen fertilization ability. The re was less pollen tube attrition after bud pollinations than after fl ower pollinations, indicating that styles of buds were less able to in hibit pollen tubes. The variance component for plants acting as pollen donors tended to be greater after flower pollinations than after bud pollinations. The lower variance in male success after bud pollination s indicates that differences among pollen donors after flower pollinat ions were due to stylar inhibition of pollen rather than differences i n pollen vigor. Since the level of variation in pollen growth after po llination to flowers was greater among clones than among ramets within clones, the differences in pollen fertilization ability are probably genetically based.