Movement of Water and Mass Transfer Into Developing Grains of Wheat

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Abstract
A method was developed for measuring the net fluxes of water (Fw) and dry matter (Fdm) 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. Fw and Fdm were measured gravimetrically as changes in weight of the grain and the contents of the capsule during 4 days. Fdm 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 Fw, or to the direction of the flow of water. Besides, Fw 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.