Shade, Establishment Method and Varietal Effects on Rhizome Yield and Curcumin Content in Turmeric.

Turmeric (Curcuma longa) is a spice and biomedical crop containing curcumin, which has potential for treatment of cancer and Alzheimer’s disease.  Cultivation of turmeric in the United States would allow greater quality assurance and reduced transportation costs compared to importation from Asia. The warm growing season in the southern United States is short relative to tropical environments where the plant is normally grown and research on cultural practices is lacking.  A split-split plot experiment was carried out in east central Alabama to assess the effects of shade (40 % shade vs no shade), establishment method (early establishment in greenhouse over heat pads vs direct seeding), and variety on rhizome yield and curcumin content.  Canonical Discriminant Analysis revealed distinctive trends based upon varietal differences, establishment methods and presence or absence of shade.  Extending the growing season by early establishment in the greenhouse increased rhizome and curcumin yield as well as curcumin concentration in lateral rhizomes.  Shade increased plant height, leaf size and fresh weight of rhizomes but an apparent increase in rhizome dry weight was not significant. Shade decreased curcumin concentration and yield in mother rhizomes, but had little effect on curcumin concentration in lateral rhizomes. An apparent increase in curcumin yield in lateral rhizomes with shade was not significant.  Significant differences among varieties were observed for rhizome yield and curcumin concentration and yield.  Results suggest that cultivation of turmeric in Alabama is feasible by extending the growing season and selection of shorter-season varieties high in curcumin.