Promotion of germination of fynbos seeds by plant-derived smoke



Fynbos is the dominant vegetation type in the Cape floristic region. Periodic fires are a natural phenomenon in fynbos and fire-stimulated seed germination has been reported for a number of fynbos species. Amongst the factors proposed as being directly responsible for the effects of fire are: heat fracturing hard seed coats, heat stimulating seed embryos, high-temperature desiccation of seed coats, ethylene and ammonia in smoke stimulating seed germination, and unknown chemical factors in plant-derived smoke and smoke extracts stimulating germination. In this study 28 fynbos species were screened for a seed germination response to smoke and/or smoke extract treatments. Twelve of these species showed a statistically significant enhancement of germination in response to treatment. For the first time smoke per se has been shown to act as a seed germination cue for fynbos species in the Asteraceae, Ericaceae and Restionaceae, and for the first time smoke extracts have been shown to enhance germination in fynbos species of Proteaceae. The most marked response to both smoke and smoke extracts was shown by seed of Syncarpha vestita (syn. Helichrysum vestitum) (Asteraceae).