The Velocity and Pattern of Assimilate Translocation in Wheat Plants During Grain Development

Abstract

The translocation of labelled assimilates from the flag leaf blade to the ear and other parts of the plant was followed in wheat, 15-20 days after anthesis. The velocity of assimilates moving through the top internode varied from 80 to 100 cm/hr and the velocity of movement down the leaf sheath was about half this value. Removing grains from the head reduced the velocity of the assimilates moving up the stem from the node and increased their downward velocity in the stem. How-ever, the rate of movement out of the leaf was unaffected by the removal of grains. With full grain development assimilates from the flag leaf moved directly from the node of insertion of the leaf up the stem to the ear. The results are discussed in relation to the vascular anatomy of wheat and the mechanism and factors controlling translocation.