Rate of acropetal transport of the xylem stream in phaseolus vulgaris

Hate of acropetal movement of the xylem stream was measured in the petioles, epicotyls, and hypocotyls of bean plants. Loss of water by intact, transpiring plants was first determined gravimetrically. Next, volume of the functional xylem in various sections of the stems was determined using radioisotope dilution techniques. Rate at which the xylem stream renewed itself to account for the overall water loss of the plant served as the basis for flow rate values.