Partitioning of C-14-photosynthate of leaves in roots, rhizome, and in essential oil and curcumin in turmeric (Curcuma longa L.)

Incorporation of photosynthetically fixed C-14 was Studied at different tim e intervals of 12, 24, and 36 h in various plant parts-leaf 1 to 3 from ape x, roots, and rhizome-into primary metabolites-sugars, amino acids, and org anic acids, and secondary metabolites-essential oil aid curcumin-in turmeri c. The youngest leaves were most active in fixing C-14 at 24 h. Fixation ca pacity into primary metabolites decreased with leaf position and time. The primary metabolite levels in leaves were maximal in sugars and organic acid s and lowest in amino acids. Roots as well as rhizome received maximum phot oassimilate from leaves at 24 h; this declined with time. The maximum metab olite concentrations in the roots and rhizome were high in sugars and organ ic acids and least in amino acids. C-14 incorporation into oil in leaf and into curcumin in rhizome was maximal at 24 h and declined with time. These studies highlight importance of time-dependent translocation of C-14-primar y metabolites from leaves to roots and rhizome and their subsequent biosynt hesis into secondary metabolite, curcumin, in rhizome. This might be one of factors regulating die secondary metabolite accumulation and rhizome devel opment.