Production and dormancy of wild oat (Avena fatua) seed from plants grown under soil waterstress

Abstract

SUMMARYIn 1974 wild oat plants grown from very dormant seed types fA, fB, fC originating from a single field, and in 1976 plants of type fB derived from another location were waterstressed from the time when the spikelets were just beginning to emerge until the seed was fully ripe. The seed production and dormancy of the seed were determined. Waterstress reduced the number of viable seeds per plant by 42% in 1974 and 49% in 1976. The number of viable seed produced on the tillers of the plants were reduced to a greater extent by waterstress than the number produced on their main stems. Some of the differences between the number of viable seeds produced by the three wild oat types were significant. In 1974, 78% of seed from stressed plants was dormant as compared with 90% of that from unstressed plants. Under a given soil moisture, the dormancy of the three types differed little, although seed dormancy was less in tiller seed than in main stem seed. In 1976 seed from stressed plants was 80% dormant, immediately after collection, whereas that from unstressed plants was totally dormant. Storage for 6 months at 25°C decreased these percentages to 17% and 90% and at 5°C to 72% and 98% respectively. Buried in soil immediately after collection, 66% of viable seed from stressed plants gave seedlings in the first autumn after burial as compared with 4% of seed from unstressed plants. Most of the seed from waterstressed plants gave rise to seedlings in the first autumn, and seed from non‐stressed plants in the second spring. The α‐amylase content was four times greater in seeds from stressed compared with non‐stressed plants.