Wound-induced ethylene and germination of embryos excised from dormant Avena fatua L. caryopses

Intact caryopses of dormant AN265 and M73 wild oat (Avena fatua L.) lines did not germinate when imbibed in water at 14°C, but germinated after exposure to ethylene during imbibition. Embryos excised from dormant caryopses and imbibed in water germinated readily. However, inhibitors of ethylene synthesis ([aminooxy]acetic acid and 2-[aminoethoxyvinyl] glycine) and ethylene action (2,5-norbornadiene and silver thiosulfate) delayed or almost completely inhibited germination of excised embryos. Embryos removed from inhibitor treatments after 15 d and incubated in water germinated normally. Except for 2,5-norbornadiene, inhibitors did not reduce germination of intact nondormant (afterripened) caryopses or embryos excised from nondormant caryopses. Reduced germination rates of embryos excised from dormant caryopses and incubated in 2,5-norbornadiene and 2-(aminoethoxyvinyl) glycine were reversed by applications of 0.05 μL/L ethylene. The results indicate that wound-induced ethylene synthesis may be responsible for germination of embryos excised from dormant wild oat caryopses.