| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 84 === Recently,the difference between air and canopy temperature(Tc-
Ta or ΔT) mearsured by infrared thermometer was used to assess-
ment of plant water status.ΔT and vapor pressure deficit( VPD )
were used for developing crop water stress index (CWSI) .The ob-
jectives of this research were to compare ΔT and CWSI to be
better plant water status indicator ,to understand the relation-
ship among the CWSI,the transpiration, the leaf water potential,
and the soil water potential of Golden Dewdrop ( Duranta repens
cv.Golden Leaves)and to investigate the optimal irrigation range
for Golden Dewdrop and Coleus （ Coleus blumei Benth ） by using
CWSI as a irrigation criterion.
The short-term(1 day)experiment showed that the ΔT of drought
treated Golden Dewdrop plants decreased from 4.0℃ to -1.62℃
after rewatering was similar that of to that of the well watered
treatment.The long-term (1 week ) experiment showed that the ΔT
of drought treated plants was 3-5℃ higher than the well watered
in golden dewdrop , and was 1-2 ℃ higher than the well watered
plants in coleus .ΔT could be a reference of plant water status
but could not be the quantifier of water stress .However , CWSI
that ranges from 0 (no stress) to 1 (maximum stress) could be an
reasonable indication of water stress.
Also by using gold dewdrop , the CWSI and other water related
physiological parameters could be established .In the experiment
period , CWSI was unstable because of the environmental various
light intensity in greenhouse .After removing the data of cloudy
and rainy days,leaf water potential and soil water potential de-
clined linearly with increasing CWSI (r2 =0.82 and 0.47, respec-
tively).The experimental period was from Oct .30 ,1995 to Nov.9,
1995 . The lower baseline of other month*s were used to replace
October*s and to calculate CWSI ,the results could offer accept-
able information.
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