Abstract
The aim of this study was mainly to elucidate the difference in the aspect of top-root interdependence between different plant types of Allium sp. with special reference to absorption of nitrogen, under the population level. As the experimental treatments, 2 planting densities, and 2 nutrient levels (Hewitt's solution), were employed in the experiment. The results obtained were as follows; 1) About the absorption of nitrogen (%), there were no significant defference between planting spaces and nitrogen levels. 2) To discuss the competition among the individual plants from a new standpoint, T/R 3-Dimensional Ratio was adopted to indicate the top-root relationship and the population structure. It is pointed out the usefulness of the index to inquire mutual relations between plants in a population.
