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 degrees C results in later flowering and reduced seed yield in plants grown from these seed compared with plants grown from seed matured at 13 degrees C, The objectives of this study were to determine the changes in seed mass and soluble carbohydrates of white lupin seed as affected by seed maturation temperature, Fourteen soluble carbohydrates were identified and quantified by high resolution gas chromatography of the trimethylsilylimidazole-derivatization products. Reducing sugars were not 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 total soluble carbohydrates were raffinose, stachyose, and verbascose. In addition to the raffinose series oligosaccharides, four series of galactosyl cyclitols were present including the galactinol series, galactopinitol A series, galactopinitol B series, and fagopyritol B1 series, Seed matured at 28 degrees C accumulated only 53 to 70% as much dry matter as seeds matured at 13 degrees C. Only minor changes in the raffinose series oligosaccharides were observed. Pinitol and the galactose-containing pinitols were more than doubled by seed maturation at 28 degrees C, but collectively, these compounds are <10% of the total soluble carbohydrates, We conclude that the effect of seed maturation temperature on the composition and concentration of soluble carbohydrates is minimal.