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You are here: Home / Picture Tutorials, Videos and maintenance information / What kind of plants can be measured?

What kind of plants can be measured?

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Almost any vascular plant can be measured in the pressure chamber.  Twigs, branches, herbs, grasses, and fruits of a variety of species have been measured successfully.

Twigs and branches

Most of the early work with the pressure chamber was done with woody plants because they are easiest to measure. Secondary lateral twigs of large trees can be used, but the entire top of seedlings may be required. In woody species the phloem (bark) should be stripped back from the cut surface about 2 cm (about 3/4″) to allow the xylem (woody portion) to protrude through the gasket.

Selecting a proper sized Compression Gland Gasket and Compression Gland Insert is important.  Ensuring that you use the proper Compression Gland Gasket and Compression Gland Insert with the proper Compression Gland Base is important not only for sealing properly but for safety also.

Herbs

Herbaceous plants are only slightly more difficult to measure than woody plants. Sealing the sample in the gasket without crushing or kinking the stem is usually the biggest problem.  This can sometimes require creative methods of measurement.

The endpoint may be difficult to determine, but a good lighting or a lighted magnifier will be helpful. The use of a microscope to aid them in seeing the endpoint is sometimes used in very small samples but such measures are usually not necessary.

With herbs it is especially important to measure the sample immediately after cutting and to use the proper rate of pressure increase.

Grasses

Measuring grass can be more difficult than round or semi-round samples.  While it is sometimes possible to measure the round portion of the stem it is normally more successful using the flat portion of a leaf blade.  The Grass Compression Gland Sealing System is normally the best way to seal the blade into the chamber. 

Fruits

Measuring fruits such as apples, oranges, or tomatoes is not difficult, but the fruit must usually be supported in the chamber. A coil spring in the bottom of the chamber is helpful. Once the sample is in the chamber measurements can proceed as with herbs.

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More Resources:

  • Instruments
    • Instrument Quick-Connect Couplers
    • Filling the Model 610 internal Portable Tank
    • Filling the Model 615, Model 615D or Model 1515D Internal Tank
    • Filling the Portable Tank
    • Sealing a sample in the Compression Gland Cover
    • Setting the Rate Valve
    • What it should look like when it’s all hooked up
  • Making the Measurements – Plant Moisture Stress
    • Interpreting Data
    • Making the Measurement of the Plant Sample
    • Measuring Leaf Water Potential in Wine Grapes
    • Measuring Stem Water Potential (SWP)
    • Measuring Stem Water Potential in Almond Trees
    • Measuring Stem Water Potential in Prune Trees
    • Measuring Stem Water Potential in Walnut Trees
    • PMS – Meaning and Importance
    • Stress levels, crop tables and information
    • Using a Pressure Chamber with Almond
    • Using a Pressure Chamber with Walnuts
    • Using a Pressure Chamber with wine grapes
    • Using a Pressure Chamber with Prunes
    • What kind of plants can be measured?
    • When to make measurements
  • Accessories to Nitrogen Gas Units
    • Installing the Almond Compression Gland Gasket and Insert
    • Installing the Grass Compression Gland
    • Using the Grass Compression Gland
    • Pressure Regulators: Do I need one?
    • Using the Grass Compression Gland with corn
    • Sealing a sample using inserts, gaskets and tools
    • Standard Sealing System

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