SECONDARY DORMANCY IN DORMOATS FOLLOWING TEMPERATURE TREATMENTS: FIELD AND LABORATORY RESPONSES

Abstract

Partially after-ripened seeds of three dormoat lines (Avena sativa L. × A. fatua L.) were treated to induce secondary dormancy before field planting in the fall. The objectives of this experiment were to evaluate the dormancy response of the treated seeds and to determine if field performance, in terms of both survival and emergence, was improved by the treatments. Treatments consisted of imbibition and incubation of seeds at two temperatures: 4 °C for 3 wk or 30 °C for 2 wk. Both treatments increased dormancy, but differences were also noted in the type of relative dormancy expressed by each seed population under laboratory conditions. Treated seeds and the appropriate untreated control seeds were sown in the field, in fiberglass mesh bags, either in early or late fall depending on the treatment. Levels of dormant seeds retrieved from the field, at the end of the fall season, varied for each dormoat line and did not reflect the induced secondary dormancy measured before field planting. The fate of these dormant seeds after exposure to winter stresses was assessed on field-retrieved material in the spring. In relation to a late sowing of untreated seeds, the treatments were effective in improving levels of viable seeds (dormant or germinating) remaining in the ground, in the spring. However, the best performance, both in survival and emergence, was obtained with an early fall planting of untreated seeds. High loss of viability was common to both treated and untreated seeds of the three dormoat lines. The major shortcoming of dormoats seems to be in the area of cold resistance of the fall dormant seeds since damage during winter played an important role in survival.Key words: Secondary dormancy, relative dormancy, dormoats, emergence