Water‐soluble Carbohydrate Accumulation in Soybean Plants¹

Abstract

Because metabolic processes in plants are dependent on water‐soluble carbohydrates (WSC), information concerning the effects of different factors on the WSC contents of plants should be useful in the development of improved practices. Soybean [Glycine max (L.) Merrill] plant samples from field fertility experiments on Webster soil (Typic Haplaquoll) were collected and analyzed during two growing seasons to study the effect of different variables on WSC contents of different plant parts at various stages of plant development. WSC in dried plant samples were extracted with hot water and determined using a phenolsulfuric acid colorimetric method with glucose as a standard. The WSC content of leaves and petioles increased between 0900 and 1300 hours daily. WSC contents generally were higher in 1971 than in 1972. Differences in WSC among cultivars and fertility levels were relatively small. Percentages of WSC in leaves increased throughout the growing season, but in stems and petioles increased only until seed development became rapid. WSC contents of stems, petioles, and pods decreased as the seeds developed. This decrease may indicate that soluble CHO (metabolically active carbohydrate) becomes a limiting factor for seed production during the seed‐filling period.

Effect of Water Deficits on Seed Development in Soybean

“…2). The pattern of mobilization in the water-deficient plants is similar to that observed in well-watered plants during the later stages of seed filling (4,22 supplied to the seed (23, 24), we measured the level of endogenous sucrose in the cotyledon tissue and estimated the concentration of sucrose within the interfacial apoplast between the testa and cotyledon symplasm. Figure 3 shows that endogenous sucrose in the controls was about 60 to 70 mg * g dry weight-' in agreement with previous estimates (7,18).…”

Contribution of Remobilized Total Dry Matter to Soybean Yield

“…[L.]) carbohydrate and nitrogen patterns have demonstrated that accumulation occurs during the flowering and pod formation periods (R1-R6, stages according to Fehr & Caviness 1977) and is then remobilized during the latter half of the seed filling period (R6.2-R7; Henderson & Kamprath 1970;Dunphy & Hanway 1976;Stephenson & Wilson 1977;Burton, Wilson, & Brim 1979;Egli et al 1980;Giaquinta et al 1985;Seddigh & Joliff 1986;Yamagata, Kouchi, & Yoneyama 1987;Egli & Crafts-Brandner 1996;Egli 1999). Initiation of remobilization is concomitant with the first signs of senescence (decline in photosynthesis, chlorophyll, and total leaf N coupled with an increase in proteolytic activity), changes that begin occurring when 50% of seed weight is obtained (Wittenbach et al 1980;Giaquinta et al 1985).…”

“…Among vegetative organs, carbohydrate concentrations were usually two to three times greater in leaves compared with petioles or stems (Kollman et al 1974;Dunphy & Hanway 1976;Ciha & Brun 1978). Patterns of seasonal starch accumulation and remobilization vary depending on the study.…”

Enhancement of Biological Nitrogen Fixation of Common Bean in Latin America

“…Studies on soybean have shown that this N drain may be high enough to decrease photosynthetic activity (Dunphy and Hanway, 1976), induce premature leaf senescence and reduce root activity (Harper, 1974, Ramon Garcia andHanway, 1976). Nutrients supplied through leaves may supplement rapidly those transferred from stems and roots, thus avoiding early leave senescence (Frith and Dalling, 1986).…”