The Campbell-Brewster (J-14) leaf press is a compact
alternative to the pressure chamber for plant water
potential determination. Data comparing the J-14
with the pressure chamber (?x) or with canopy
temperatures (Tc) and crop water stress index (CWSI)
are limited. All three J-14 end points (exudation
from cut or uncut leaf edges or darkening of
interveinal areas) 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.
Our data shoved a species-related reliability of the
J-14. The J-14 produced r2 values above 0.7 for
soybean for all but comparisons with CWSI or Tc
minus air temperature (?T), and for corn for ?x
only. The J-14 did not perform well for tomato or
rapeseed. Failure of J-14 or ?x, to correlate well
with CWSI suggests difficulty with CWSI measurement
under humid southeastern conditions
