Material of measurement
High resolution plant growth (HRPG) installation based on LVDT sensor technology. The plant is connected to the iron core of the LVDT. A small traction is maintained with a spring linked to a support (1). The LVDT signal is converted to a DC signal by the GDU units (Sensor interface) converted to digital number by an A/D card in a computer and finally sampled by a specific software. Twelve LVDT sensors are present. Temperature, light and relative humidity sensors signals are processed (amplified, filtered and scaled in the sensor interface), they are also sent to the computer via the A/D card. When needed or when the plant growth is such as the iron core is not optimally positioned within the LVDT sensor, the control software individually and specifically triggers an I/O card which controls the motors on the supports. The rotation of a spindle repositions the plant-connected core and its LVDT sensor accurately.
Measurement of growth rhythm
Floral stem growth dynamics of A. thaliana (Ler). A. Raw growth dynamics with interruptions by the motor lift-up (see text) from L:D 12:12 to continuous light and temperature. B. Integration response once the lift-ups have been removed. C: Same data as B, but expressed on a rate of growth basis (differencing). D: Five different plant's rate of growth measurements done in parallel (empty dots) with their mean dynamics (plain line in L:D 12:12. Data has been filtered in order to remove high frequency fluctuations.