Releasing primary dormancy in Avena fatua L. caryopses by smoke-derived butenolide

The effect of smoke and smoke-derived butenolide in releasing dormancy of caryopses (referred to as seeds) of the economically important weed Avena fatua L. was studied. Seeds of A. fatua are dormant after harvest. Both smoke-water and butenolide, applied continuously, removed dormancy in darkness at 15, 20 and 25 degrees C and slightly at 30 degrees C. Butenolide was very active at a concentration of 10(-8) M. Butenolide at 10(-8) M was also able to remove dormancy at 20 degrees C when applied for 12 or 24 h at 4 degrees C or for 3 to 24 h at 20 degrees C. Sensitivity to butenolide decreased with longer pre-incubation times in water. This compound was less effective in releasing dormancy in the light than in darkness. Dormancy release by butenolide involves induction of cell-cycle activity just before coleorhiza protrusion. Stimulatory effects of smoke-water and butenolide were also observed in respect of seedling growth and vigor.