Studies on the Environmental Factors Affecting the Seed Germination and Seedling Growth of Several Pasture Species : 1. Effect of light intensity on the growth of seedlings of some grasses and legumes

Abstract

The authors have been studying since 1955 the effects of environmental factors upon seed germination and seedling growth of grasses and Iegumes to furnish some basic data in the hope of contributing to the establishment and management of grassland. In this report the results dealing with light intensity on the growth of seedlings are presented. 1) The light intensity in a vegetation is roughly proportional to the height from the ground, and that near the surface is markedly reduced, showing the importance of light for the growth of seedling. 2) In shading experiments, it was found that the morphological characters of the seedlings could be classified into two types : (1) Characters diminishing with the diminuation of light intensity (A Group), and (2) Characters increasing with the decrease of light intensity while shading was slight and decreasing responding reversely to the advanced degree of shading (B Group). Majority of the characters belonged to B Group. In the response to shading, generally speaking, underground organs responded more remarkably than top organs. Among the species, the seedlings of gramineae were affected more strongly than those of legumes. 3) The seed size had large influence on the length of the period of exhaustion of stored nutrients, amount of growth living on stored nutrients, and the growth of seedling under shading.