Movement of Water and Mass Transfer Into Developing Grains of Wheat

Abstract

A method was developed for measuring the net fluxes of water (F_w) and dry matter (F_dm) through the stalk attaching the grain to the rachis. After the removal of the bracts, the base of the grain was embedded in plastic material of low permeability, and a capsule containing water or solutions of known water potential was sealed over the grain. F_w and F_dm were measured gravimetrically as changes in weight of the grain and the contents of the capsule during 4 days. F_dm was independent of the water potential gradient between the rachis and the atmosphere within the capsule (surrounding the grain), and was not related either to the size of F_w, or to the direction of the flow of water. Besides, F_w was too small to be consistent with a mechanism for the transport of assimilates involving proportional unloading of solute and solvent into the apoplastic phase of the grain.