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XYLEM WATER HOLDING CAPACITY AS A SOURCE OF ERROR IN WATER POTENTIAL ESTIMATES MADE WITH THE PRESSURE CHAMBER AND THERMOCOUPLE PSYCHROMETER
Author(s) -
Hardegree Stuart P.
Publication year - 1989
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1989.tb11322.x
Subject(s) - xylem , hygrometer , thermocouple , symplast , biology , botany , seedling , shoot , water content , water transport , horticulture , environmental science , materials science , humidity , water flow , soil science , composite material , thermodynamics , geology , physics , apoplast , cell wall , geotechnical engineering
The pressure chamber and the thermocouple psychrometer often provide different values when used to estimate plant water potential. One hypothesis to explain the discrepancy between instruments is that water movement between the xylem and symplast occurs during pressurization in the pressure chamber. Pressure chamber and thermocouple psychrometer measurements of Pinus ponderosa (Laws.) seedling shoots and mature Quercus agrifolia (Nee) shoots showed that the discrepancy is greater for Quercus. It was hypothesized that the xylem water content‐water potential relationship of these species would explain the magnitude of the discrepancy between instruments. The xylem water holding capacity alone, however, does not explain the difference between species. The larger discrepancy in Quercus is likely due to a greater volume of water held in the xylem relative to the volume held in the symplast.