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A comparison of pressure chamber, leaf-press, and canopy temperature for four species under humid conditions

Sojka, R.E. and Sadler, E.J. and Camp, C.R. and Arnold, F.B. (1990) A comparison of pressure chamber, leaf-press, and canopy temperature for four species under humid conditions. Environmental and Experimental Botony. 30(1):75-83.

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Numerous techniques are currently available for measurement of
plant water status in field environments, including pressure chambers and indices based upon
infrared-determined canopy temperatures. The Campbell-Brewster (J-14) leaf press has been
promoted as a compact alternative to the pressure chamber for plant water potential determination.
In-depth comparisons of the J-14 (ΨJ) with the pressure chamber (Ψx) or with canopy
temperatures (Tc) and crop water stress index (CWSI) have been limited, and an evaluation of
the technique in a humid environment was needed. All three J-14 end points [exudation from
cut (ΨJc) or uncut leaf edges (ΨJu) or darkening of interveinal areas (ΨJd)] were highly correlated
among themselves for the four species studied. Correlations of J-14 end points with other stress
indicators from unstable diurnal periods were poor. None of the water status indicators correlated
well with leaf diffusive resistance. Our data showed a species-related reliability of the J-14. The
J-14 produced r2 values above 0.7 for soybean [Glycine max. (L.) Merr.] for all but comparisons
with CWSI or Tc, minus air temperature (ΔT), and for corn (Zea mays L.) for Ψx only. The J-14
did not perform well for tomato (Lypersician esculentum Mill.) or rapeseed (Brassica napes L.), and
is probably best regarded only as a relative indication of plant water status in the absence of
calibration with other techniques. Failure of Ψx or J-14 to correlate well with CWSI underscores
difficulty with CWSI measurement under humid conditions.

Item Type: Article
NWISRL Publication Number: 0694
Subjects: Mass Import - unclassified
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:53
Last Modified: 03 Jan 2017 18:13
Item ID: 528