GROWTH OF SOYBEAN SEEDLINGS AS AFFECTED BY COTYLEDON SHADING AND ITS RESERVES

Effect of the shading of the cotyledons of soybean (Glycine max, Merrill) and the contribution of its reserves for the growth of seedlings of cv. IPAGRO 21, was evaluated in greenhouse. Six treatments were established by the combination of excision and shading of the cotyledons. Dry weights of cotyledons, leaves, stem and roots, and the area of cotyledons, were determined at 2, 5, 8, 11 and 14 days after emergence. Approximately 50% of the reserves stored in the cotyledons were exhausted in the first two days after emergence. The shading of the cotyledons decreased seedling growth until the 11th day after emergence. Seedlings with one or two excised cotyledons showed less growth than intact seedlings.