Kinetics of upward bending response of gravistimulated snapdragon
shoots.
Discussion
'Simulated time-lapse photography'
For the first time, the bending of a snapdragon shoot was captured on
'film' using 'Simulated time-lapse' photography. By using the computer to
overlay the images, one can get a view of the complex upward movement. In
this experiment, so called, 'overshoot' and migration of the bending zone
along the shoot were clearly demonstrated.
Some recommendations can be made with respect to measuring the gravitropic
response of plant shoots. Although an APT in combination with a strip
chart recorder is in theory the system of choice for measuring the
response accurate and over a long period of time, a few remarks can be
made. The Gould transducer is probably not sensitive enough to record the
upward bending of snapdragon shoots accurately. Other disadvantages are
that only one shoot at a time can be monitored and that the bending angle
is restricted to a maximum angle of 30o (see box 1). Gould
instrument systems also offers more sophisticated transducers which only
need a displacement of 60 microns for full scale deflection. However these
transducers, designed for medicel systems, are very costly (up to $6,000).
Another system which can be helpful in determining the gravitropic
responses of several shoots at the same time, is the use of a digital
camera and a computer. If pictures are automatically taken at regular
intervals, the angle can be measured with image processing software like
Adobe PhotoshopTM. The price of these cameras is much lower
than that of an advanced APT and it can provide a better insight in the
whole gravitropic curvature. However a system like this could be less
accurate in recording the initial bending response.
