Norwegian-grown Jerusalem artichoke (Helianthus tuberosus L.): morphology and content of sugars and fructo-oligosaccharides in stems and tubers.

BACKGROUND

Two field trials growing Jerusalem artichoke (Helianthus tuberosus L.) are discussed. Twenty genetic variants were compared in order to find genotypes suitable for Norwegian production. A second trial investigated the above-ground part of early and late variants.

RESULTS

The highest yield (28.7 t ha(-1)) and highest amount of tubers per plant was obtained in early variants, e.g. the white Tysnes gave 1.72 kg tubers plant(-1). Early variants had a markedly lower portion of smooth tubers. Late variants gave the most preferable tuber shape, but low yield. Only a weak correlation was found between dry matter content and total content of fructo-oligosaccharides (FOS) (r = 0.255) in the tubers. The mean content of FOS including sucrose through all variants was found to be 116 g kg(-1) fresh weight (FW) or 550 g kg(-1) dry weight (DW). The average chain length of FOS in the tubers was found to be DP3.9. There was no difference in tuber FOS content between early and late variants. The highest above-ground amount biomass was found for the late variants when harvested in September. The content of soluble carbohydrates was found to be highest in stalks in August (sucrose and FOS major compounds).

CONCLUSION

Early variants give the highest tuber yield under Norwegian growing conditions. Late variants give highest above-ground biomass.