PLANT-DERIVED SMOKE AND SMOKE EXTRACTS STIMULATE SEED-GERMINATION OF THE FIRE-CLIMAX GRASS THEMEDA-TRIANDRA

Plant-derived smoke and aqueous extracts of smoke stimulate germinatio n of dormant seed of the important fire-climax grass Themeda triandra (redgrass). The positive germination response to smoke increased as th e state of seed imbibition increased. Furthermore, aqueous smoke extra cts significantly increased seed germination at optimum and sub-optimu m germination temperatures. Ethrel and ethylene, at a wide range of co ncentrations, failed to increase T. triandra seed germination, indicat ing that ethylene is not the active component of plant-derived smoke. Similarly, ash or aqueous ash extracts failed to stimulate germination . In contrast, aqueous smoke extracts prepared from burning fynbos veg etation and grass leaf material stimulated T. triandra seed germinatio n. The bioactive component of plant-derived smoke may originate from a commonly occurring source, possibly being a thermal breakdown product of hemicellulose or cellulose.