World

How seeds germinate after bushfires

Australian scientists have identified the chemical in smoke that makes plant seeds germinate after bushfires, a discovery that could reap huge benefits for the agricultural sector. A team of Australian scientists has become the world's first research team to pinpoint the previously unknown chemical, called a butenolide, which induces germination in a variety of plant species including celery, parsley and echinacea. While it has long been known that many types of seed in wildfire-prone areas from the American West to the Australian Outback germinate after exposure to fire, the specialization of this response has only started to be understood recently. Some seeds are stimulated or helped to open by the heat of fire, but in others, chemicals produced during combustion induce germination. In some cases, the seeds seem to pick up the cue from contact with charred plant material, but often, mere exposure to smoke is all that's needed to get a seed going. Smoke particles can affect seeds many miles downwind from a fire, and horticulturalists often use "smoke water" to induce growth of native prairie species, as well as to promote the growth of plants that normally are independent of fire for germination. But the process of putting "smoke tents" over plots of seeds or otherwise artificially reproducing the effects of wildfire can be cumbersome, even dangerous, so having the active ingredient in hand has practical advantages as well as aiding future research on just how the compound stimulates growth. Benefits to horticulture seen

"Given the broad and emerging use of smoke as an ecological and restoration tool, the identification of this compound as the main contributor to the germination-promoting activity of smoke could provide benefits for horticulture and disturbed-land restoration," said Gavin Flematti, professor of biomedical and chemical sciences at the University of Western Australia and lead author of a report on the discovery published by the journal Science. Scientists say the discovery could give farmers a multimillion-dollar edge in weed control by allowing them to speed up the germination of dormant seeds. "With further testing, this could help farmers who want to control crop weeds, without having to wait so long for the seeds to germinate again before being eradicated," said Kingsley Dixon, the scientist who directed the Western Australian study. The researchers noted that because the compound is derived from burning cellulose, which is a component of all plants, it would be present in the smoke of all natural fires.