DORMANCY STUDIES IN SEED OF AVENA FATUA: I. THE POSSIBLE ROLE OF GERMINATION INHIBITORS

Abstract

When aqueous extracts of hull and caryopsis of Avena fatua are chromatographed, two inhibitory regions can be detected. These two inhibitors appear to be present in the hull and caryopsis in approximately equal amounts per unit weight of tissue. Evidence has been brought forward to show that the inhibitory effect of the hull in intact dormant seeds cannot be ascribed solely to the inhibitors present in the hull, nor does interference with gaseous exchange by this tissue account for its effect. Experiments have shown that isolated caryopses from dormant seeds germinate only when in contact with liquid water. Evidence from several experiments indicates that the hull may prevent leaching of inhibitors from the caryopsis which then allows of germination. It has been shown that inhibitors very readily diffuse out of the caryopsis on moist filter paper and that this process is retarded by the hull. Treatment with high oxygen concentrations, which promotes germination of very dormant seeds, appears to result in a reduction of inhibitor level before visible germination. In the induction of secondary dormancy under anaerobic conditions there is a marked increase in the total inhibitor level of the caryopses.