Plant moisture condition analyzer Plant water potential analyzer

The plant water potential analyzer is a type of instrument used to measure plant water potential (PSI) and its components, as well as to extract sap from xylem vessels for component analysis. It can be used to study the water relationship of plants and the relationship between plants and the environment. Suitable for research in plant physiology, ecology, agriculture, forestry, and forage. Based on this, it is an important instrument for teaching and scientific research to guide the rational water use and drought resistant breeding of crops, forests, and grasses. It is easy to operate, fast, and suitable for indoor and outdoor fieldwork.

　　Measurement principle of the instrument

Plants in the soil plant atmosphere continuous system, their roots continuously absorb water from the soil, while their leaves continuously move towards the surrounding areas

The environment loses water, and in this water potential gradient system, there is also a water potential gradient between plant roots, stems, and leaves, which causes the xylem vessels to

The small water column is affected by the negative pressure of low water potential in the air, forming a pulling force for the upward transportation of moisture. When plant branches or leaves are cut off

When the tight water column in the conduit breaks, the water column will contract inward from the incision towards the upper end. Load the cut material into the instrument

In the pressure chamber of the device (see operating procedure below), extend the cut end outside and seal it, apply pressure, and make the inside of the branch or leaf

The tension is rebalanced to push the small water column back to the surface of the incision, and all the pressure is the water potential value of the plant.

　　Installation of instruments

1. Power on instructions: Close the "air valve" and "exhaust valve" of the instrument.

2. Quick connector (new model)

Connect the other end of the metal hose to the gas cylinder through a transition joint. The gas cylinder should be filled with nitrogen or compressed air. must not be allowed

Use flammable and explosive gases such as oxygen and hydrogen.

4. Use a small wrench to secure the air nozzle connecting the instrument to the pressure hose, and tighten the connection with a large wrench. Note: The new water potential meter has been equipped with a quick connector.

　　Determination of water potential

1. Preparation of instruments:

Remove the pressure chamber cover and install metal gaskets and rubber seals of corresponding sizes according to the requirements of the measured material,

Close the air valve and exhaust valve. In order to avoid the impact of pressure chamber heating and air drying caused by outdated instrument pressurization. can

Place a damp piece of gauze at the bottom of the pressure chamber (note: do not block the pores) or cover the material.

1. Sampling and Sample Assembly:

Cut the test sample (branches, stalked leaves, Poaceae leaves, or aboveground parts of seedlings, etc.) with a small knife blade, including the stem and

Branches should have a length of more than 3cm to facilitate fixation onto the sealing gasket. If the sample cannot be measured immediately, it should be promptly removed

Put it in a plastic bag or slightly damp gauze to prevent moisture loss. The cut surface of the material should be as smooth as possible, otherwise thin verticals should be made

Straight and smooth cutting.

Thread the material through the hole (seam) on the cover to expose the cutting end by a few millimeters. rotate

The pressure cap with a flower wheel clamps the material tightly (to achieve sealing without damaging the material, this requires operational experience). To reduce water loss, the cover should be replaced as soon as possible, allowing it to descend along the groove and rotate clockwise. (If the gasket slides, tweezers can be used to fix it.)

Close the pressure chamber.

　　Remember not to be careless and apply pressure without properly covering the lid to avoid the risk of the pressure chamber lid coming out!!

　　Pressure measurement

1. Close the gas valve of the plant water potential meter and then open the gas cylinder valve slightly (not too wide), check the gas pressure gauge, and when the display is close to the gas cylinder pressure, promptly close the gas cylinder valve.

2. Slightly and very slowly open the air valve, causing the pressure gauge and numerical display to slowly increase.

Observe the material cross-section at a 35 ° angle next to the upper part of the pressure chamber using a magnifying glass. When the cut surface appears moist and liquid is about to seep out, immediately close the air valve. Record the reading on the pressure gauge, which is the water potential pressure of the plant.

3. After the reading is completed, open the exhaust valve to release the gas in the pressure chamber. Once the pressure gauge returns to zero, open it

Remove the material from the pressure chamber cover, close the exhaust valve, and perform the next measurement.

Precautions

1、 The pressure chamber cover must be closed in place. After the measurement is completed, the gas inside the pressure chamber must be fully discharged before opening the chamber cover

Replace the sample.

2、 When operating, remember not to place your hands and face above the pressure chamber to avoid accidentally not covering the pressure chamber cover or material not being properly installed

If fixed properly, it may slide out and cause damage.

3、 The pressurization rate should not be too fast, as it may cause biased data due to conduction hysteresis effects.

4The The pressure gauge on the instrument should be sent for quality inspection and calibration after a period of use.

5、 Do not use the instrument under pressure. When the pressure is neglected, the safety valve will make a deflated sound, and the pressure should be stopped immediately.

6、 The gas cylinder should be filled with nitrogen or compressed air. Do not use flammable and explosive gases such as oxygen and hydrogen.

7、 If the instrument malfunctions, please contact the dealer or authorized personnel and do not disassemble the instrument without authorization. Otherwise, the consequences will be borne by oneself.