GROWTH OF SOYBEAN SEEDLINGS AS AFFECTED B Y COTYLEDON SHADING AND ITSRESERVES

Effect of the shading of the cotyledons of soybean (Glycine max, Merri ll) and the contribution of its reserves for the growth of seedlings o f cv. IPAGRO 21, was evaluated in greenhouse. Six treatments were esta blished by the combination of excision and shading of the cotyledons. Dry weights of cotyledons, leaves, stem and roots, and the area of cot yledons, were determined at 2, 5, 8, 11 and 14 days after emergence. A pproximately 50% of the reserves stored in the cotyledons were exhaust ed in the first two days after emergence. The shading of the cotyledon s decreased seedling growth until the 11th day after emergence. Seedli ngs with one or two excised cotyledons showed less growth than intact seedlings.