Trace Gas Emissions and Smoke-Induced Seed Germination

Dormant seeds of a California chaparral annual were induced to germinate by smoke or vapors emitted from smoke-treated sand or paper. Nitrogen oxides induced 100 percent germination in a manner similar to smoke. Smoke-treated water samples inducing germination were comparable in acidity and concentration of nitrate and nitrite to nitrogen dioxide (NO$_2$)-treated samples. Vapors from smoke-treated and NO$_2$-treated filter paper had comparable NO$_2$ flux rates. Chaparral wildfires generate sufficient nitrogen oxides from combustion of organic matter or from postfire biogenic nitrification to trigger germination of Emmenanthe penduliflora. Nitrogen oxide-triggered germination is not the result of changes in imbibition, as is the case with heat-stimulated seeds.