GERMINATION RESPONSE TO PHYTOCHROME DEPENDS ON SPECIFIC DORMANCY STATES IN WILD OAT (AVENA-FATUA)

Effects of brief red and far-red light on germination of seeds from do rmant lines of wild oat (Avena fatua L.) were studied in combination w ith mechanical injury to the seed coat, application of gibberellin A,, or changes in relative humidity during afterripening. Aberrant germin ation responses to phytochrome action were observed in the mechanicall y injured seeds in some of the lines, i.e., brief red light inhibited or delayed germination induced by injury, and immediately following fa r-red light cancelled the negative effects. Phytochrome action influen ced germination of the gibberellin-treated seeds in a normal fashion, although effects of the gibberellic acid and brief red light on germin ation were not additive. Brief red light inhibited germination of seed s afterripened in zero relative humidity; the same light promoted germ ination of those in 30 and 60% relative humidity. Germination response to phytochrome in wild oat depends on specific seed dormancy states, illustrated by genetic origins, dormancy-breaking methods and afterrip ening conditions.