IRRIGATION, FERTILIZER, HARVEST DATES AND STORAGE EFFECTS ON THE REDUCING SUGAR AND FRUCTOSE CONCENTRATIONS OF JERUSALEM ARTICHOKE TUBERS

Abstract

Several management practices were imposed on four Jerusalem artichoke (Helianthus tuberosus L.) accessions to determine changes in tuber yield, sugar content and the percentage of fructose and glucose in the hydrolyzed soluble sugar extracts. The fructose concentration in the reducing sugars declined from 82.3 to 74.2% from 6 September to 24 October. Storage of tubers at 2 C for up to 11 wk reduced the mean level of fructose from 78.2 to 68.0% and had a variable effect on reducing sugar concentration. Supplemental irrigation lowered the reducing sugar concentration significantly, while fertilization had no affect on any quality parameters. The Morden accession, M6, produced the best combination of high tuber yield (37.4 t/ha), reducing sugar concentration (16.3%) and fructose concentration in the reducing sugars (77.4%). Although a long period of growth was desirable to produce maximum yields of both tubers and total sugar, it was accompanied by a reduction in the ratio of fructose to glucose. This crop does not appear to require a high level of management to produce a good quality carbohydrate product.