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Enabling better global research outcomes in soil, plant & environmental monitoring.

Plant-Pressure-Ecotron (PPE)

The Plant-Pressure-Ecotron (PPE) is an experimental system to measure plant transpiration rates and the water potential of intact plants at the soil-plant-atmosphere continuum.

The system consists of three main parts: the pressure chamber, the transparent hood, and the control unit.

The plant to be studied is planted into the pressure chamber, which contains the soil and the plant roots. The transparent cuvette is placed on top of the pressure chamber and contains the plant leaves. A sensor attached to a trimmed leaf transmits a signal to the controller, which regulates the chamber pressure to maintain the xylem sap at the point of bleeding. PPE measures this ‘balancing pressure’ P that is needed to bring the leaf xylem to atmospheric pressure, which is equivalent to the leaf xylem suction prior to pressurisation.

The transpiration rates will be determined by the difference in humidity between the ingoing and outgoing air, which circulates inside the cuvette using a fan. The illumination of the plant with photosynthetically active radiation (PAR) can be regulated.

Technical Specifications

Installation area (width x height x depth):

  • ca. 1,200 mm x ca. 945 mm x ca. 500 mm

Other sizes of the pressure chamber and the transparent hood are available upon request.

Pressure Chamber:

  • pressure chamber (iØ 156 mm, height 328 mm) up to 20 bar, incl. certificate for pressure chamber
  • temperature sensor  Pt-100 for measuring in pressure chamber headspace or soil cylinder
  • oxygen sensor (automatic control oxygen in headspace)
  • pressure sensor (automatic control of pressure)
  • flange plate with opening (Ø6 mm) and holder for a plant seedling
  • soil core cylinder made of PVC transparent (iØ 111 mm, height 270 mm)

Transparent Hood:

  • acrylic cuvette (diameter: 200 mm, height: 505 mm)
  • 4x LED boards (wave length maximum: red channel with 733, 677, 737 nm, white/blue channel with 448/580, 454/642 nm)
    • channels independently dimmable of each other in the range of 0 to 100%
    • light intensity of both channels up to 1,300 µmol/(s•m²)
  • air humidity and temperature sensors in air in- and out-take
  • fan to homogenise air
  • PAR sensor
  • adapter ring for pressure chamber with tube, capillary and wire connector
  • meniscus sensor to automatically gain the actual meniscus level in dependence of the tension of the plant seedling
  • humidity unit to automatically control air humidity and the air change rate in the transparent hood
    • rel. air humidity ca. 40 % to ca. 90 %
    • air flow rate: 0 to 10 l/min
  • water filled packed column with glass beads and recirculation pump

Control Unit:

  • Ethernet Port
  • 110 or 230V AC
  • gas sockets for compressed air and nitrogen incl. stop, discharge and safety valves
  • PLC, Siemens SPS 7
  • 7” colour display
  • project generation, manual and automatic operating mode, graphical visualisation of actual data,
  • status LEDs for overpressure notification

A gas supply of more than 20 bar is needed.