KARRIKINOLIDE – A PHYTOREACTIVE COMPOUND DERIVED FROM SMOKE WITH APPLICATIONS IN HORTICULTURE, ECOLOGICAL RESTORATION AND AGRICULTURE

Here we provide a brief overview of the action of smoke in stimulating germination and review the phytoreactive nature of the active chemical in smoke responsible for eliciting a range of germination and growth responses in seeds and plant tissues. The discovery of the active chemical in smoke, here referred to as karrikinolide (from the generic class of compounds karrikins, with karrikinolide previously referred to as ‘butenolide’ or 3-methyl-2H-furo[2,3-c]pyran-2-one), provides significant new opportunities for promoting germination and seedling growth in agriculture, horticulture and restoration as well as providing a remarkable tool for scientific investigations into the action of fire in ecosystems. Smoke, derived from burning plant material, has been shown to promote the germination of seeds of plant species from many ecosystems, as well as agricultural and horticultural species. Karrikinolide induces germination in a comprehensive and indicative selection of species known to be smoke-responsive, including native species from California, South Africa, Australia and a range of horticultural and crop species. Of note is that a range of well known economically important weed species respond to field and laboratory application of karrikinolide. Furthermore, seed germination activity of karrikinolide has been demonstrated at concentrations as low as parts per trillion, illustrating the potent germination-promoting activity of the molecule. In field situations this equates to 2 - 5 g per ha of active ingredient, levels that represent commercially viable application rates. Research is now focused on the mode of action of karrikinolide in promotion of seed germination and plant vigour as well delivery systems for karrikinolide in horticulture and agricultural systems.