STUDIES ON THE BIOLOGY OF WILD OATS. I. DORMANCY, GERMINATION AND EMERGENCE

Abstract

Mature seeds of wild oat (Avena fatua L.) from Alberta were completely dormant when freshly harvested. About 46% of the seeds lost their dormancy during storage for 33 wk at room temperature. Gibberellic acid was very effective in overcoming dormancy in freshly harvested or stored seeds. Water extracts from dormant wild oat seeds were more inhibitory than water extracts from non-dormant seeds to germination of wild oat seeds. A number of chemicals, viz., nitrates of potassium, ammonium and sodium, cytokinins (benzyladenine, kinetin), and thiourea, were effective to varying degrees in stimulating the germination and emergence of seeds. Percent germination and emergence of seedlings was maximum at temperatures ranging from 10 to 21 C, although germination and emergence were slower at 10 C than at the higher temperatures. A temperature of 32 C was detrimental to normal germination and emergence. Maximum seedling emergence occurred when soil moisture was maintained at 50 or 75% of the field capacity. At field capacity moisture levels, no seedlings emerged and nearly all the seeds had rotted within 11 days of planting. Planting depths of 2–8 cm were best for seedling emergence. From greater planting depths the rate and percent emergence were greater for larger seeds than for smaller or medium-sized seeds (separated on the basis of kernel weight). Time to maximum emergence was 8, 11–13 and 13–17 days from depths of 0.5–3 cm, 4–12 cm and 16–20 cm, respectively. Practical implications of some of these findings in a wild oat control program are discussed.