Simulation of competition between barley and wild oats under different managements and climates

Abstract

Abstract The simulation of competition among different plant populations growing within a common ecosystem should be based upon the explicit simulation of the processes whereby these populations compete for irradiance, water and nutrients. In the mathematical ecosystem model presented here, each plant population is simulated independently within a common soil-atmosphere ecosystem. Exposure to irradiance is calculated from the vertical distribution of leaf area, calculated in turn from the elongation of each internode, sheath (if monocot) or petiole (if dicot), and leaf on each tiller or branch of each population within a common canopy. Access to water and nutrients is determined by the vertical distribution of root length and surface area, calculated from the elongation of primary and secondary root axes of each population through a common soil profile. The model reproduced losses of grain yield by barley ( Hordeum vulgare L.) from 0 to 70% caused by different densities and emergence dates of wild oats ( Avena fatua L.) that were recorded from several field trials in central Alberta. The sensitivity of simulated yield losses to wild oat competition under different climate and management was then compared to that reported in the literature. Examination of model results led to the hypothesis that sensitivity to competition among plant populations is determined by the availability of water, nutrients and other ecological resources at the site of study. Contrasting results of such competition in the literature may perhaps be explained by this hypothesis, but the absence of detailed data for soil and climate from experimental sites prevents rigorous testing.