SOLUBLE CARBOHYDRATES IN WHITE LUPIN SEEDS MATURED AT 13 AND 28-DEGREES-C

Maturation of white lupin seed (Lupinus albus L. cv. Ultra) at 28 degr ees C results in later flowering and reduced seed yield in plants grow n from these seed compared with plants grown from seed matured at 13 d egrees C, The objectives of this study were to determine the changes i n seed mass and soluble carbohydrates of white lupin seed as affected by seed maturation temperature, Fourteen soluble carbohydrates were id entified and quantified by high resolution gas chromatography of the t rimethylsilylimidazole-derivatization products. Reducing sugars were n ot detected, and sucrose was 10 to 15% of total soluble carbohydrates in the axis and 12 to 20% in the cotyledons. Seventy to 80% of the tot al soluble carbohydrates were raffinose, stachyose, and verbascose. In addition to the raffinose series oligosaccharides, four series of gal actosyl cyclitols were present including the galactinol series, galact opinitol A series, galactopinitol B series, and fagopyritol B1 series, Seed matured at 28 degrees C accumulated only 53 to 70% as much dry m atter as seeds matured at 13 degrees C. Only minor changes in the raff inose series oligosaccharides were observed. Pinitol and the galactose -containing pinitols were more than doubled by seed maturation at 28 d egrees C, but collectively, these compounds are <10% of the total solu ble carbohydrates, We conclude that the effect of seed maturation temp erature on the composition and concentration of soluble carbohydrates is minimal.