EXPERIMENTS ON THE MECHANISM OF INDUCED DORMANCY IN WILD OATS, AVENA FATUA L.

Abstract

Experiments were conducted on the factors involved in the induction of dormancy in wild oats. It was shown that when the supply of air reaching the embryo of imbibed seeds is restricted, changes occur in the caryopses so that when the seeds are subsequently dehulled and the caryopses exposed to air they are unable to germinate. Induction of dormancy is greater at 25 °C than at 7 °C. The site of the mechanism controlling induced dormancy is in the embryo or endosperm rather than in the seed coat or hulls. If dormant caryopses are punctured they germinate even when the wound is covered with lanolin or agar. Inhibitors were found in methanol extracts of both dormant and non-dormant caryopses, but it was concluded that they are not responsible for induced dormancy. An inhibitor which leaches from the hulls of wild oats completely stops growth of excised embryos but dormancy can be induced in the absence of hulls. Dormant caryopses absorb 2,3,6-triphenyl-tetrazolium chloride but are unable to reduce this dye. The mechanism of induced dormancy is discussed.