Increasing Speed, Accuracy, and Safety of Pressure Chamber Determinations of Plant Moisture Stress

The pressure chamber provides a simple, accurate, rapid, and practical means of measuring plant moisture stress (PMS) (2, 3). PMS is a measure of the internal moisture stress that occurs in the wood vessels, or xylem, of plants. Forest scientists often use the term xylem water potential for PMS and express PMS as negative bars or megapascals (MPa), i.e., 1 MPa = 10 bars. In addition to its use in diagnosing plant moisture stress, the measurement of PMS is particularly useful in analyzing the environmental conditions associated with stress in nurseries and established plantations and in trouble-shooting establishment problems (1). The pressure chamber is now being routinely used to evaluate seedling moisture stress by nursery personnel and regeneration specialists.