Studies on the Growth Behavior and Quality of Forage Crops in the Warm Areas of Japan : I. Influence of growing season on the growth, structure and chemical composition of the corn plant at its different growing stages

It has been conceived that the quality of forage crops is generally inferior in the warmer areas than that in the colder areas of Japan, though scarcely reliable proofs for the fact having been given hitherto. In the present study, the authors investigated the effects of various growing seasons in Kyushu on the growth behavior, structure and chemical composition of corn plants the samples of which were seeded April 15, June 15, and August 15. respectively. A good many reports given in the past on the physiological studies of environmental effects upon such crop plants seem to have more or less unduly neglected the problems of the age of the plant materials for experiments. In the study by the present authors, an early variety, Northwestern Dent Corn, were conveniently used as material, because the final number of leaves on the main stem showed only a very little variation among individual plants of this variety, and so the growth stages could be identified so clearly that the effects due to the environments were distinguished from those due to the age of the plant. Internodes of a definite position from the sample plants were used in the physical, histological and chemical examinations. It was found as the result that the period from planting to tasselling was shortened by late planting, and that the leaf emerging in the main stem was faster when planted June 15 or August 15 than when planted April 15. The plant was tallest when planted June 15. The period, from planting to beginning of elongation of internode was longer when planted April 15 than, when planted June 15 and August 15. The lower internodes of corn plant were longer, and the middle internodes were short when planted April 15. The internodes were harder in the lower portions of stem than those in the higher portions. The hardness of internode increased with advance of growth stage. However, there was not remarkable difference between the hardness of internode of each plot at the same growth stage. When corn was planted August 15, the internode was harder at the former part of growing stage than those of the other two plots. The degree of lignification of internode was approximately parallel to the hardness. Crude protein content and crude ash content were higher through out the growing season when planted August 15 than when planted April 15 and June 15, but crude fiber content was not lower in the former case than that of the latter cases.