Mass flow
The movement of dissolved nutrients with bulk water toward a root surface. Transpiration and water uptake help maintain this flow through the root zone.
In root-zone nutrition, mass flow carries dissolved ions toward roots as plants take up water. It differs from diffusion, which moves an ion down its own concentration gradient, and from root interception as roots grow into new substrate.
Arrival at the root surface does not guarantee uptake. Membranes and transport proteins regulate which ions enter, while root-zone chemistry affects which forms remain available. After uptake, water and minerals move through the xylem Xylem The vascular tissue that carries water and dissolved minerals from root to leaf. Flow is one way and pulled by transpiration, so anything that slows transpiration slows delivery. by a different transport process.
Nutrients differ in how strongly they depend on mass flow. Calcium delivery to rapidly growing shoot tissue is especially sensitive to water uptake and transpiration because calcium has limited redistribution through phloem.