Measurement with a Scholander Pressure Chamber means, that the water status of the plant is directly measured via it's leaf water potential. This technique is based on research done by P.F. Scholander in the year 1965. Our models PMS, M600, M615, M1000, M1505D, M1515D and M1505DEXP are made by the worldwide first commercial manufacturer of Scholander Chambers, and offer unmatched security during handling and for taking measurements. Since more than 40 years, of activity of this company, never any accident occurred with instruments from this manufacturer.

Advantages

The status of the plant and not the one of the soil is basis for the irrigation decision. Measurements with a Scholander Pressure Chamber provide solidly founded information on water availability in the whole rooted area of a plant.

Working Principle

Taking a reading with a Scholander pressure chamber means, that the tension of the xylem water in a plant is measured directly. In the early morning before sunrise a leaf sample is cut from the plant and sealed air-tight in the pressure chamber. Only the cut end of the petiole sticks out a few millimeters. Then the chamber is pressurized slowly. As soon as water appears at the cut surface of the petiole, the equilibrium is reached, i.e. the pressure inside the chamber equals the tension of the xylem water column in the leaf before cutting. This value also reflects the soil water potential in the whole rooting zone of this plant.

Another approach is the measurement of the stem water potential. Here the sample is put into a reflective plastic bag and sealed air-tight. Due to the plastic bag no gas exchange is possible, and after some hours / over night, the equilibrium between the leaf water potential of the bagged sample and the stem water potential of this plant is reached and can be measured. The advantage of this technique is, that measurements of stem water potentials can be done also during the day.

Typical Applications

Scholander pressure chambers are commonly used in vineyard and orchard irrigation scheduling and in research, but almost any vascular plant can be measured in the pressure chamber.