Carbohydrate-related changes in sweetpotato storage roots during development

The quantity and pattern of carbohydrate-related changes during storage roo t development differed among six sweetpotato cultivars [Ipomoea batatas (L, ) Poir, 'Beauregard', 'Heart-o-Gold', 'Jewel', 'Rojo Bianco', 'Travis', and 'White Star']. Measurements were taken for individual sugars, total sugars , alcohol-insoluble solids (AIS, crude starch), and dry weight (DW) at a-we ek intervals from 7 to 19 weeks after transplanting (WAT) in two separate y ears. Sucrose was the major sugar during all stages of development, represe nting at least 68% of total sugars across all cultivars and dates, Pairwise comparisons showed 'Heart-o-Gold' had the highest sucrose content among th e cultivars, Sucrose content increased by 56% for 'Heart-o-Gold' over the 1 2 weeks of assay, ranking first among the cultivars at 17 and 19 WAT and po ssessing 27% more sucrose than the next highest ranking cultivar, 'Jewel', at 19 WAT. Fructose content profiles varied among and within cultivars, 'Be auregard' showed a consistent increase in fructose throughout development w hile 'Whitestar' showed a consistent decrease. The other cultivars were inc onsistent in their fructose content profiles, Glucose content profiles were similar to those for fructose changes during development, The relationship between monosaccharides was fructose = 0.7207 x glucose + 0.0241. Cultivar s with the highest fructose and glucose content could be selected by breede rs after 13 WAT, Early clonal selection for high sucrose and total sugars i s less promising because substantive changes in clonal rank occurred for su crose and total sugars after 15 WAT. Cultivars ranking the highest in total sugars had either more monosaccharides to compensate for a lower sucrose c ontent or more sucrose to compensate fur a lower monosaccharide content. Th e relationship between DW and AIS was similar (AIS = 0.00089 x DW), and BW and AIS increased with time for most cultivars, Cultivars with high DW and AIS can be selected early during storage root development.