Changes in Carbohydrate Contents of Germinating Soybean Seeds¹

Abstract

Changes in dry weights, total soluble carbohydrates, and individual sugars in the cotyledons and embryo axes of soybean ( Glycine max (L.) Merrill) seeds from a relatively high oil variety, ‘Hawkeye’ (22%), and a low oil line, P.I. 86002 (16%), were determined over a 13‐day germination period. Total dry weights of cotyledons decreased while those of embryo axes increased as the seed germinated. Total soluble carbohydrates accounted for 15% of the total dry weights in cotyledons of ungerminated seeds and decreased more rapidly throughout the germination period than did cotyledon weights. Total soluble carbohydrates of the embryo axes increased steadily during the first 5 days and declined thereafter. Similar patterns of utilization of soluble carbohydrates were observed for Hawkeye and P.I. 86002 even though their cotyledons differed 6% in oil content. Stachyose, raffinose, and particularly sucrose were the dominant sugars found in ungerminated soybean seeds. Stachyose and raffinose declined rapidly in the cotyledons by day 3 and disappeared by day 9 of germination. Sucrose increased slightly during the first 3 days but decreased steadily after the third day. Fructose and glucose appeared in day‐1 cotyledons, with the former reaching a maximum value on the fifth day and the latter on the ninth. Stachyose, raffinose, and sucrose were also the major sugars found in the 0‐day embryo axes. Stachyose and raffinose were depleted completely by day 3 in the embryo axes of P.I. 86002 and by day 5 in Hawkeye. Sucrose decreased between day 5 and day 13 for P.I. 86002 but showed irregular change in Hawkeye during this period. Fructose and glucose appeared in day‐1 embryo axes, continued to increase through day‐5 of germination, and decreased thereafter.