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Water Potential Measurements of an Intact Plant‐Soil System 1
Author(s) -
Hoffman Glenn J.,
Splinter William E.
Publication year - 1968
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1968.00021962006000040023x
Subject(s) - water potential , evapotranspiration , soil water , relative humidity , loam , environmental science , diurnal temperature variation , water content , humidity , agronomy , soil science , atmospheric sciences , ecology , biology , physics , geotechnical engineering , engineering , geology , thermodynamics
Thermocouple psychrometers were used to measure the water potential of an intact plant‐soil system. The system consisted of a young tobacco plant grown in a container of fine sandy loam soil. The effects of soil water potential, diurnal fluctuations, and atmospheric relative humidity on the leaf water potential within a leaf and at different locations on the plant were studied. Water potential was found to decrease from the base of the leaf to the tip. Leaves at the base of the plant were found to have lower water potentials than leaves near the middle. The soil water potential decreased linearly with time as evapotranspiration occurred in the system. The site of measurement on the leaf, atmospheric relative humidity, and diurnal variations were found to affect the relationship between leaf and soil water potential. At a constant relative humidity a linear relationship was obtained when the leaf water potential was measured at the base of the bottom leaves or at a given time each day to eliminate diurnal variations. In general, however, the relationship between leaf and soil water potential was not found to be linear. Soil water potential, atmospheric relative humidity, and diurnal variations were found to reduce the leaf water potential by at least 100% in tobacco if altered within the range found under field conditions.