The effect of density and plant arrangement on the performance of individual plants in barley and wheat crops

Abstract

The spatial relationships and growth of individual plants were studied in barley and wheat crops to determine the influence of size and distance of neighbouring plants on the development of individuals within the population. Plants were harvested individually, and their positions recorded by X and Y coordinates. The dry weights within quadrats were categorized in 10 weight classes and plotted for visual analysis. A reciprocal equation was used to relate the weight of individual plants to 'competitive pressure' of near neighbours. The estimate of competitive pressure was based on the weight and distance of neighbours. Both visual analysis and numerical analysis failed to find a direct effect of space available or the location of near neighbours on the growth of individual plants. It is suggested that in dense cereal crops differences in time of emergence and quality of soil environment may over-ride the advantage of an increased spatial environment for individual plants.