When plants are growing rapidly, the size of the growth induced
water potential field becomes larger and it has not
been observed in the adjacent mature or slowly growing
tissues (Boyer and Nonami 1993, Nonami 1993). it is important
to note that when the growth-induced water potential is
present and growth rates become larger, the water potential
in the zone of elongation becomes more negative than that
in the water source (Ikeda eta/. 1996, Nonami 1993). The
existence of tension and the negative pressure were confirmed
in the elongating tissue of soybean stems
Whenever the growth process is occurring, the absorption
of water is necessary to sustain cell expansion. Thus, the
growth-inducad water potential must be present between
the elongating cells and the water source. The value of the
growth-induced water potential was determined by a pressure
chamber when growth of soybean seedlings was
reduced by low temperatures, and it was found that the size
of the growth-induced water potential was decreased proportionally
as the growth rates were decreased by low
temperatures (Boyer 1993). These findings were confirmed
by using the psychromater in the same tissue, indicating that
water absorption associated with growth under chilling stress
was regulated by the size of the growth-induced water
potential