Adaptation strategies of contrasting oat genotypes to planting pattern and population densities

Adjusting planting pattern and population density may be an effective approach to reducing chemical use for weed control in small grain cereal crop production. Such study may also lead to the identification of biological traits for use in plant breeding. Field and controlled growth room studies were conducted to (1) characterize adaptive strategies of contrasting oat genotypes; and (2) determine if there was a difference in oat genotypes representing different growth type on weed suppression in response to planting density and row spacing. The results indicate that under field conditions, oat genotypes with prostrate leaves (OA1256-1) showed significantly lower weed biomass than oat variety with erect leaves (OA1228-1) at high population density, especially under high weed pressure. Greater yield was observed for the prostrate variety at the medium density under high weed pressures, and the opposite was observed at high density cultivation at low weed density. Under the controlled growth room conditions, with increasing plant densities, intensive competition among individuals led to an overall reduction in grain yields for both varieties. However, the erect variety showed reduced aboveground biomass allocation and lower yield, whereas the prostrate variety showed decreased allocation to the roots and increased allocation to the panicles under increasingly competitive environment. Our findings provided a novel rationale for a planting strategy based on plant type selections.