Members of the family Proteaceae have extremely low mature fruit : flower (FR
: FL) ratios (range 0.001–0.163) compared with other temperate,
hermaphroditic, woody perennials. Sutherland’s (1986) survey of FR : FL
ratios indicated that compatibility was an important factor explaining levels
of fruit set. The role of compatibility in regulating FR : FL ratios was
tested in five closely related species of Grevillea
(Proteaceae). Species-specific compatibility was compared using the
self-compatibility index (SI = ratio of selfed fruit set to crossed
fruit set) calculated at fruit initiation to minimise the confounding effect
of other post-fertilisation fruit losses, such as inbreeding depression and
pre-dispersal predation. Fruit : flower ratios at initiation ranged from
0.041–0.249, and at maturity 0.015–0.096.
Grevillea species showed highly variable breeding
systems: G. linearifolia was self-incompatible (SI
= 0.003), G. sphacelata,
G. mucronulata, and G. oleoides
were partially self-compatible (SI = 0.07–0.28) and
G. longifolia was self-compatible (SI = 0.61).
Intrapopulation variability in the level of self-incompatibility was high in
all species but G. linearifolia. The correlation between
SI and FR: FL ratios was non-significant, indicating that compatibility has a
minimal effect on fruit set in the Grevillea species
studied, and that these data, together with other data on proteaceous species
do not support trends observed in Sutherland’s survey. Low FR : FL
ratios resulted from of a combination of pollen limitation, and high levels of
flower and fruit predation.
The role of flowering plants, Hibiscus sabdariffa and Crotalaria juncea in coffee ecosystem to diversity of insect pollinators and coffee fruit set