Abstract
The process of curcumin accumulation into rhizomes of turmeric and yellow zedoary was examined. The curcumin concentration of turmeric was higher in seed rhizome than in mother rhizome and daughter rhizome, and it was not detected in shoot and roots. Dry weight of seed rhizome in both turmeric and yellow zedoary decreased after planting from May to July, while dry weight of primary rhizome increased rapidly from September to November. This vigorous rhizome growth was observed especially from September to October in yellow zedoary, and from September to October (in 2006) and from October to November (in 2007) in turmeric. The curcumin concentration of seed rhizome in turmeric markedly increased with decrease in dry weight and resulted in higher concentration than that of primary rhizome. The curcumin concentration of primary rhizome increased from September to October and little increased or slightly decreased from October to November. On the other hand, in yellow zedoary the curcumin concentration of seed rhizome slowly increased from September to May, while that of primary rhizome decreased significantly from September to October. Such decrease in curcumin concentration resulted in a low curcumin content of yellow zedoary. The curcumin contents increased with the increase in the rhizome yield, showing the importance of the rhizome yields for the improvement of the curcumin contents. The curcumin concentration was stable during the storage period in both turmeric and yellow zedoary.
