FACTORS AFFECTING THE PERSISTENCE OF AVENA FATUA

Abstract

The effect of storage temperature upon after-ripening of wild oats, the induction of dormancy under aerobic and partially anaerobic conditions, and the effect of wetting and drying upon viability, germination, and seedling development were investigated.Warm, dry conditions were more conducive to after-ripening or loss of dormancy than cold, humid conditions. Most of the seeds stored alternately at 18 and 40 °C after-ripened in 3 years. At temperatures below 18 °C after-ripening was not complete after 5 years.Dormant seeds became more dormant when exposed to germinative conditions and subsequent drying. Induction of dormancy by this means (aerobic conditions) can prolong the life span of wild oats.After-ripened seeds became dormant when soaked in soil at 60% moisture (limited oxygen). The development of dormancy was affected by temperature, duration of soaking, and drying of the seeds after soaking. The effect of drying was reversible and appeared to depend upon the amount of previous induction. Mortality increased markedly when soaking was prolonged at 25 °C. Increased mortality, resulting from repeated wetting and drying, only accounted for a small part of the losses observed in seeds on the soil surface.Interruption of imbibition (8 to 32 hours) by drying resulted in faster germination when seeds were rewetted. One-third of the seeds that imbibed water for 48 hours before being dried for 7 days grew vigorously when rewetted.