This osmotic pressure is called root pressure . Root pressure is observable at night when evaporation is low and excess water collects in droplets around special openings near the tip of grass blades. Such water loss in its liquid phase is known as guttation .
Root pressure can only provide a modest push in the overall process of water transport.
Its greatest contribution maybe to reestablish the continuous chains of water molecules in the xylem which often break under the enormous tensions created by transpiration. This gradient is necessary for plants to transport water . Pure water has the highest potential while a saturated solution of ions etc. would have the lowest potential. Water potential is highest when water is a liquid and lowest when water is a gas in air. See below for my explanation of water transport.