Some aspects of competition for light in potatoes and sugar beet

Abstract

1. In experiments on potatoes and sugar beet, interplant competition for light was varied by altering the spacing distance between plants grown in containers, while competition for water and nutrients was eliminated.2. In both experiments the relative growth rate was 10 % less in closely spaced plants because net assimilation rate was greatly decreased; leaf area ratio was increased. Increasing competition for light decreased mineral nutrient uptake.3. It was considered that differences between the treatments in the intensity of competition for light was greater in these experiments than it normally in the field because differences in leaf area index were greater. The leaf area of widely spaced plants was smaller in these experiments than in the field; this was thought to be due to a more limited supply mineral nutrients in the former.4. In both species, the greatest crop growth rates were observed at leaf-area indices well below the maxima attained. The likelihood that observed crop growth rates were near maximal under the prevailing environmental conditions is discussed.