(Abstracted from Quandong, vol 24, No 3). Many plants need to experience a fire before their seeds will germinate. For a long time it was assumed that it was the heat from such events that provided the critical trigger for germination. However, in recent years certain seeds have been shown to respond to smoke, even when there is no fire.
Now, for the first time, researchers have narrowed the trigger down to a specific compound in smoke. “Plant ecologists Jon Keeley and D. J. Fotheringham, of Occidental College in Los Angeles, collected seeds of Whispering Bells, a common California wildflower that proliferates after fires, and exposed them to either straight nitrogen dioxide, (NO2,) or wood smoke (which contains NO2).
With as little as one minute’s exposure in either situation, the researchers managed to trigger germination in every seed. They had the same success when they exposed seeds to NO2 vapor from sand, paper and water that had absorbed smoke two months earlier.