Studies on Leaf Formation in Rice Plants. : III. Effects of some environmental conditions on leaf development

Abstract

Size, structure and development of mature leaves of rice plants were investigated in relation to population density and nitrogen fertilization. Leaves of densely-grown plants are much longer and somewhat wider than those of sparsely-grown ones. However, size of shoot apices in the former is rather smaller than in the latter. This contradictory relationship is attributable to the difference in duration of intercalary and ground meristem activity at the "late stage" of leaf development. Yet leaves of densely-grown plants have no "shade-leaf" structure (low stomatal density, expanded venation) so often found in densely-grown dicotyledonous plants. The explanation may lie in the difference between the developmental patterns of leaves in both types of plants. Leaves from plants that received nitrogen fertilizer are longer and wider than those not fertilized with nitrogen. Shoot apices and immature leaves of nitrogen-fertilized plants are always larger. Size of shoot apices, in this case, is directly related tothat of mature leaves. However, observation of the structure of mature leaves indicates that the intercalary and ground meristems of immature leaves also play important roles in determining the size of mature leaves.