Developmental and Environmental Effects on Assimilate Partitioning in Canada Thistle (Cirsium arvense)

Abstract

Under field conditions, more photoassimilate moved to roots of Canada thistle at the bolt than at the bud, flower, or postflower stages. Similarly, greater photoassimilate accumulated in roots of Canada thistle in the greenhouse at the rosette and bolt than at the flower bud stage. Growth chamber experiments indicated that environmental conditions typical of fall, and possibly early spring, favored photoassimilate movement to the root and superseded growth stage control of assimilate partitioning. Allocation of assimilate within the root was strongly influenced by growth stage, with most assimilate being utilized for growth at the rosette stage and for fructan reserves in bolt and flower bud stages.