Effect of Maturity on Seed Sugars as Measured on Near-Isogenic Soybean (Glycine max) Lines

The objective of this study was to investigate the effect of maturity and field temperature on the concentration of sucrose, raffinose, and stachyose in soybean seed in two sets of near-isogenic lines of Clark and Harosoy. The maturity of each line within each set varied, but all lines from each set shared a common genotypic background. The results showed that in the Clark isoline set, maturity had a negative linear relationship (sugars decreased as days to maturity increased) with the concentration of sucrose (r(2) = 0.83 in 2004; r(2) = 0.94 in 2005), stachyose (r(2) = 0.51 in 2004; r(2) = 0.51 in 2005), and combined sugars (sucrose+raffinose+stachyose) (r(2) = 0.83 in 2004; r(2) = 0.91 in 2005). In the Harosoy set, there were significant negative relationships between maturity and sugars only in 2005 for sucrose, stachyose, and combined sugars. In the Clark set, temperature had a significant positive relationship with sugars in 2004 (sugars increased as temperature increased), but significant negative relationship in 2005. In the Harosoy set, there was a significant negative relationship between field temperature and sugars only in 2005. The contribution of maturity to the total variation in sugars was significantly higher than temperature. It was concluded that the effect of genotypic background and maturity genes on sugar concentration depended on the type of sugar.