Germination response to phytochrome depends on specific dormancy states in wild oat (Avena fatua)

Abstract

Effects of brief red and far-red light on germination of seeds from dormant lines of wild oat (Avena fatua L.) were studied in combination with mechanical injury to the seed coat, application of gibberellin A3, or changes in relative humidity during afterripening. Aberrant germination responses to phytochrome action were observed in the mechanically injured seeds in some of the lines, i.e., brief red light inhibited or delayed germination induced by injury, and immediately following far-red light cancelled the negative effects. Phytochrome action influenced germination of the gibberellin-treated seeds in a normal fashion, although effects of the gibberellic acid and brief red light on germination were not additive. Brief red light inhibited germination of seeds afterripened in zero relative humidity; the same light promoted germination 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 afterripening conditions. Key words: Avena fatua, dormancy, mechanical injury, gibberellin A3, phytochrome, relative humidity.