Assimilate distribution patterns and carbohydrate concentration changes in organs of Solidago canadensis during an annual developmental cycle

Abstract

At different stages in the growth cycle the short-term translocation pattern of 14C-labelled assimilates was determined together with carbohydrate concentration changes in two Solidago canadensis L. populations growing on abandoned pasture sites in southern Ontario. Tagging whole shoots with 14C revealed that (1) a high (50–70%) proportion of assimilated carbon is retained by leaf tissue, (2) the proportion of assimilated carbon incorporated in the aerial stem increases during shoot extension but declines later during inflorescence development, (3) the proportion of assimilated carbon translocated to the inflorescence during flowering and fruiting is considerably in excess of its dry weight contribution, and (4) underground tissues, even the new rhizomes which develop in late season, account for a comparatively small proportion of assimilated carbon. Tagging individual leaves with 14C during reproductive development showed that the proportion of leaves exporting assimilates to the new rhizome system progressively increases, while that supplying the inflorescence decreases, after August and that individual leaves do not simultaneously export carbon to the inflorescence and new rhizomes. Carbohydrate analysis showed that early shoot development is associated with a marked reduction in carbohydrate status of both roots and rhizomes, which is subsequently restored, and that roots and rhizomes retain a storage function for at least 2 and 3 years, respectively.