We found that the positive phototropic response
could be observed at fluence rates from 0.1 µmol
.
m
-2.
sec
-1
to 100 µmol
.
m
-2.
sec
-1
(Figure 2). The response increased
with increasing fluence rate up to about 10 µmol
.
m
-2.
sec
-1
,
with no reversal of curvature detected at any of the
fluence rates tested. Except for the different direction, the
fluence rate dependence for the positive phototropic
response elicited by red light was similar to those reported
for negative blue-light-induced phototropism in roots of
Arabidopsisby Sakai et al.(2000), who found maximal
curvature in the range of 10 – 100 µmol
.
m
-2.
sec
-1