J. Jpn. Soc. Soil Phys.
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**Inﬂuence of Water and Salt Stress on Stem Flow Rate ofSoybean Plant (Glycine max Merrill)
Osamu ASAI*, Kengo ITO** and Masateru SENGE*** United Graduate School of Agricultural Science, +ῌ+ Yanagido, Gifu /*+ῌ++3-, Japan** Faculty of Applied Biological Sciences, Gifu University, +ῌ+ Yanagido, Gifu /*+ῌ++3-, Japan
Abstract
The objective of this research is to examine the inﬂuence of water and salt stress on the stem
ﬂow rate of soybean planted in sandy clay loam, loamy sand, and rock wool. The experiments ofwater stress in sandy clay loam and loamy sand showed that the daily stem ﬂow rate wasinﬂuenced by soil moisture potential than di#erence of soil texture when the soil water content
changed in the range of available soil moisture. The experiment of salt stress in rock wool
showed that if the electrical conductivity of water in rock wool was the same, the daily stem ﬂow
rates became di#erent due to the history of liquid fertilizer addition. Furthermore, the daily stem
ﬂow was constant under less than ,kPa of osmotic potential, but decreased abruptly whenosmotic potential increased more than , kPa. If the matric and osmotic potentials were low, thestem ﬂow rates became a maximum at 0 hours later after light period started. However, as thematric and osmotic potentials increased, the daily stem ﬂow decreased and the peak of stem ﬂow
rate did not become clear.
Key words : Water Stress, Salt Stress, Heat Balance Method, Stem Flow Rate, Soybean

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68

mote and Stem Flow Gauge Methods in Soybean
Canopies as A#ected by Soil Water StatusB,Japanese Journal of Crop Science, 0- (.) : 00.ῌ01*.

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Sakuratani, T., Aoe, T. and Higuchi, H. (+333) : Re῎ῌ0X!" EC£verse ﬂow in roots of Sesbania rostrata measured using the constant power heat balancemethod, Plant cell and Environment, ,, : ++/-ῌ
++0*.
Sakuratani, T., Clothier, B.E. and Green, S.R. (+331) :Measurements of Sap Flow in the Roots, Trunkand Shoots of an Apple Tree Using Heat Pulse
and Heat Balance Methods, J. Agr. Met., /- (,) :+.+ῌ+./.

 5+33+6 : as0!a'@A JKLM .0 5.6 : ,0/ῌ,02.
Sakuratani, T. (+321) : Studies on Evapotranspirationfrom Crops (,) Separate Estimation of Transpiration and Evaporation from a Soybean Field without Water Shortage, J. Agr. Met., ., (.) : -*3ῌ-+1.
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Sameshima, R., Sakuratani, T. and Takenouchi, A.

£(+33/) : Relationship between Transpiration Rateof Soybean Plants (Glycine max Merr. Cv. Enrei)   and Soil Water Content Estimated by Stem Heat  !"#$% &'Balance and Heat Probe Methods, J. Agr. Met., /+()#*+,-./ 0 (,) : +/-ῌ+/1.
Senock, R.S. and Ham, J.M. (+33-) : Heat balance sapῌ ῐ ῏ ῍1234 5,**,6 : 789:;;<=>? 9ﬂow gauge for small diameter stems, Plant cell@A ++ 5,6 : /+ῌ/0.
Baker, J.M. and Van Bavel, C.H.M. (+321) : Measurement of mass ﬂow of water in the stems ofand Environment, +0, /3-ῌ0*+.

ῌῌDc 5+3306 : !s078"  JZ 0. 506 : ++3ῌ+,0.

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Yamagishi, J., Akita, S. and Takanashi, J. (+33*) :Inoue, Y., Sakuratani, T. and Shibayama, M. (+33.) :Time-course of Respiration and its Relation to

Remote and Real-Time Sensing of Canopy Tran-

Water Conditions in Various Plant Species, Ja-spiration and Conductance BComparison of Re-pan. Jour. Crop Sci., /3 (+) : +03ῌ+1-.

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