The Effect of Wounding on Primary Dormancy in Wild Oat (Avena fatua) Caryopses

Abstract

Mechanical wounding broke dormancy and promoted germination of primary dormant pure-line wild oat (Avena fatua L. # AVEFA) caryopses that were in the first physiological stage of dormancy. Caryopses incubated in petri dishes responded to wounding by germinating more rapidly than wounded caryopses incubated in soil. There was no difference in germination between wounded and lanolin-covered wounded caryopses when incubated in soil. The less dormant AN265 caryopses responded to the wounding treatment more rapidly than the more dormant caryopses of M73 in both petri dish and soil incubation systems. Chlorocholine chloride (CCC), an inhibitor of gibberellic acid (GA) biosynthesis, reduced the germination rate of wounded AN265 and M73 caryopses above and at 1 mM, respectively. Application of 25 mM CCC to wounded dormant AN265 caryopses decreased the level of hexose in the embryo to 47% of the control level. There was no significant effect of CCC on the endosperm hexose, embryo and endosperm imbibed fresh weight, and sucrose and starch content. The results suggest GA or GA biosynthesis is the limiting factor to germination.