Effects of Shading during the Early Part of Growing Period of Soybean Plants on Their Growth and Their Nitrogen and Carbobydrate Contents

Abstract

Soybean plants of variety Ou No.13, planted on May 31st, 1954, were shaded from June 8th to July 3rd, with marsh-reed screen which absorved about seventy five percent of the solar radiation. During the period of shading, the stems of the plants were slender, nitrogen content was lower and the carbohydrate contents especially of nonreducing sugars and starch were very lower than those of the control plants unshaded. After the shading treatment was stopped the starch and nonreducing sugars in the stem and leaves were accumulated conspicuously and the elongation of the stem ceased, and the axillary bud of the first leaf developed into a branch which was not seen in the control plants. Afterwards, the plants previously trated began to elongate again and at last their stem length became equal to that of the control, but the weights of leaves and stem were smaller. The date of flowering was delayed one day and the content of nitrogen was larger and the carbohydrate contents were smaller than those of the control. Consequently, the growth of the plants once treated with shading were delayed remarkably.