Evaluation of carbohydrates in Pukekohe Longkeeper and Grano cultivars of Allium cepa.

The storage, soluble, and structural carbohydrates of two onion cultivars, the hard, pungent Pukekohe Longkeeper (PLK) and the softer, milder Houston Grano, were analyzed to determine differences that might be related to their response to sulfur nutrition received during growth as well as their postharvest attributes and end-use suitability. PLK tissue contained 1.37 times more dry matter than Grano and was composed of more fructan and sucrose and less glucose and fructose than Grano [corrected] There were also differences in neutral sugar content, especially galactose, and the amount, size, and content of pectin fractions soluble in chelator and weak alkali. These two onion cultivars differed in their capacity to take up sulfur, but there was no statistical association between sulfur supply and any measured dry matter component.