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.) li nes did not germinate when imbibed in water at 14 degrees C, but germi nated after exposure to ethylene during imbibition. Embryos excised fr om dormant caryopses and imbibed in water germinated readily. However, inhibitors of ethylene synthesis ([aminooxy]acetic acid and 2-[aminoe thoxyvinyl] glycine) and ethylene action (2,5-norbornadiene and silver thiosulfate) delayed or almost completely inhibited germination of ex cised embryos. Embryos removed from inhibitor treatments after 15 d an d incubated in water germinated normally. Except for 2,5-norbornadiene , inhibitors did nor reduce germination of intact nondormant (afterrip ened) caryopses or embryos excised from nondormant caryopses. Reduced germination rates of embryos excised from dormant caryopses and incuba ted in 2,5-norbornadiene and 2-(aminoethoxyvinyl) glycine were reverse d by applications of 0.05 mu L/L ethylene. The results indicate that w ound-induced ethylene synthesis may be responsible for germination of embryos excised from dormant wild oat caryopses.