Breeding System of Dryandra quercifolia and D. formosa (Proteaceae)

Abstract

Hand pollinations were used to investigate the timing of stigma receptivity and the breeding system of two commercial cut flower species, Dryandra quercifolia Meiss. and D. formosa R.Br. Stigmas of both species showed peak receptivity at 2–6 days post-anthesis, D. quercifolia was receptive immediately after anthesis while D. formosa showed little pollen tube germination until 2 days post-anthesis. Observation of fresh pistils with an environmental scanning electron microscope revealed the stigma of both species to be wet. For D. quercifolia, maximum groove dimensions and exudate area commenced at 3 days post-anthesis and continued until day 12. A different pattern was observed for D. formosa stigmas; maximum groove dimensions and exudate area were reached at 4 days post-anthesis and decreased thereafter. Both species showed overlap in the time of maximum observed pollen tube counts, groove openness and exudate area. These factors were consistently higher in D. quercifolia than in D. formosa. Exudate production was lower in pollinated than in unpollinated D. formosa stigmas. Pollen tube and seed set data indicate a mixed breeding system for both species, with self-pollination less favoured and often resulting in post-zygotic abortion of seeds. Dryandra formosa was more self-compatible than D. quercifolia.