The bubble potometer is generally considered to provide a go

The bubble potometer is generally considered to provide a good assessment of the potential for water uptake in a plant over time, whereas a pressure bomb provides a better \"snapshot\" measurement of the actual water potential of the plant as a function of the water conditions that existed in the field at the moment the stem was cut. Why?

Solution

It is because in case of pressure bomb the sap or water will be visible at the end of the stem at a particular pressure. The sap will be forced to release out of the xylem at the given pressure and hence the pressure is equal and opposite to the water potential of the leaf. Where as in case of bubble photometer the transpiration of the leaf only can be measured.