The promotion of seed germination of Cape Erica species by plant-derived smoke

Abstract

Seeds of 40 ericaceous species were screened to obtain an indication of how important the smoke cue is for germination in the Ericaceae of the Cape. The improved germination following smoke treatment shown by 26 of the 40 species tested suggests that under natural conditions smoke from fynbos fires may provide an important cue for triggering seed germination in this family. The degree of improvement in germination following smoke treatment ranged from 164% in the case of Erica taxifolia to 7571% in the case of E. glauca var. glauca and 8100% in E. clavisepala. It is suggested that the 9 species which showed a 1000% or more increase in germination following smoke treatment form a group in which smoke is likely to be the major cue for germination. In those species in which there is a lesser response, smoke may be one of a number of germination cues which include heat, the need for 'warm' and cold stratification and alternating high and low incubation temperatures. Amongst the species responding to smoke treatment were a number of species of particular horticultural importance (as ornamentals). These include E. curvirostris, E. formosa, E. glomiflora, E. pinea and E. phylicifolia. The smoke treatment ensures a much greater efficiency when propagating from seed and this should make more plants available to the horticulture industry.