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On the Pressure Chamber Technique for Estimating Leaf Water Potential in Sorghum 1
Author(s) -
Blum A.,
Sullivan C. Y.,
Eastin J. D.
Publication year - 1973
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/agronj1973.00021962006500020047x
Subject(s) - thermocouple , pressure vessel , calibration , sorghum , xylem , hygrometer , fertigation , pressure measurement , sweet sorghum , chamber pressure , horticulture , materials science , botany , environmental science , agronomy , biology , mathematics , humidity , composite material , mechanical engineering , statistics , physics , engineering , thermodynamics , fertilizer , metallurgy
The purpose of this work was to re‐evaluate the pressure chamber technique for estimating leaf water potential in sorghum [ Sorghum bicolor (L.) Moench], with special reference to problems associated with leaf sample crushing under pressure and pressure rate increase inside the chamber. Pressure chamber readings were compared to Spanner‐type thermocouple psychrometer readings on leave of five sorghum genotypes at several stages of growth. A leaf sample holder, constructed from Silicon rubber and accomodated into a brass flange, reduced leaf crushing under pressure. It was found that pressure chamber readings (xylem pressure) cannot be directly used as estimate of leaf water potential, but should be corrected according to a calibration against a thermocouple psychrometer determinations of leaf water potential. Different rates of pressure increase in the chamber affected the regression between xylem pressure and leaf water potential. The regression improved with a greater pressure rate increase as indicated by smaller error variance estimate. No differences were detected between genotypes in this regression. This technique is, therefore, useful if worked out according to a calibration curve at a standard rate of pressure increase.