The dormancy of wild oat seed (Avena fatua L.) from plants grown under various temperature and soil moisture conditions

Summary Wild oat plants of types fA, fB and fC were grown at a constant 15 or 20°C during the period of seed maturation. Seed of the three types differed little in dormancy when grown at 15°C, but at 20°C a larger proportion of seeds of type fA were dormant compared with fB or fC. Overall, dormancy of seed produced at 15 and 20°C was 97 and 63% respectively. Plants of another collection of type fB were grown from seed at 15 or 20°C with or without water stress applied only from the time of panicle emergence. Water stress and high temperature reduced viable seed production. Seed dormancy was tested immediately after collection by planting the seed in soil, and by Petri dish tests. Further Petri dish tests were made after 6 months storage. Seedling emergence in the first autumn from seeds of plants matured without water stress at 15°C was 10% compared with 30% for seeds grown at 20°C. Seeds grown with water stress at 15°C gave 47%, and at 20°C 78% emergence. The majority of emergence from seeds formed at 15°C without water stress occurred in the second spring after burial. Petri dish tests support these findings and suggest that seeds produced in hot dry summers are less dormant than those produced in cool moist ones.