STUDIES ON THE PERSISTENCE OF AVENA FATUA

Abstract

In an attempt to determine the persistence of wild oat seeds in the soil, naturally shattered and threshed seeds of Avena fatua L. were: (a) buried at depths ranging from 0 to 25 cm in Regina heavy clay, (b) left on the surface of the soil after harvest, (c) distributed on the surface and covered after 0, 3, or 6 weeks of exposure. The persistence of seeds receiving each treatment was measured by determining the number of viable and dormant seeds after various intervals of time There was essentially no difference in the persistence of naturally shattered and threshed seeds. Loss of viable seeds was always rapid within the first year or two especially near the surface. A few seeds were still viable after nearly 7 years in the soil. Deep burial of seeds (below 5 cm) extended the period of persistence and should be avoided. Mortality of seeds near the surface was high especially during the first winter. Cultivation in mid-July had little effect on persistence. Covering the seeds after harvest stimulated germination in some years. Even without cultivation depletion was as great the following June. Samples with a high percentage of dormant seeds did not necessarily persist the longest. The pattern for loss of viable seeds was similar regardless of the initial percentage of dormant seeds. Variations in the number of dormant seeds at various times indicated that some induction of dormancy occurred.