The allocation of dry matter in seedling of the common bean (Phaseolus vulgaris L.) depends on the nutrient content in the cotyledons on principle of germination. The importance of these structures for the growth of the seedling ranges from the time of germination to the emergence of the seedling and the time when the simple leaves can realize photosynthesis. The objective of this research was to study and quantify the distribution of dry matter from the stage of germination until senescence of cotyledons during the seedling stage. Two experiments were conducted using the common bean variety Cacahuate-72, one in a greenhouse and another in growth chamber with a constant temperature of 25oC. To determine the dry weight of the structures sampling was carried out at different ages of the seedling. The stem accumulated more dry matter than the root, 56% and 44% respectively. The distribution of dry matter in the shoot structures was in the following order: simple leaves 60%, hypocotyl 25%, epicotyle 8%, petioles 5% and fi rst trifoliate leaf 2%. Root dry matter was distributed in the following order: secondary roots 46%, adventitious roots 42%, taproot 10% and tertiary roots 2%. The cotyledons exhausted its reserves of nutrients by the 18th day and they senesced at the same time. At the time of senescence of the cotyledons the hypocotyl structure was longer than the stem. Considering the root, secondary roots presented more length and were the most abundant in number. The input of fertilizer to the soil is necessary when cotyledons are beginning the process of senescence
