An Autonomous Plant Cuvette for Advanced Climate Control and Gas Exchange Measurement

In a joint project a cuvette system securing optimized plant growth is developed and tested. It is equipped for compensational measurement of CO₂ & O₂ exchange and aimes at the cultivation of fast germinating and growing plants from dry seed for 8…12 d in space. The prototype of flight hardware is now in use. The cuvette consists of two parts connected by flanges, a base of metal and an acrylic lid. It provides about 1.5 L plant space. Internal components are thermo-electric dew-point air conditioning, sensors for CO₂ & O₂, air pressure, air & heat exchanger temperature, and an absorber for gas contaminants. Peripheral parts are novel dosimetric pumps, two for pure CO₂ & O₂ (2 μL per stroke) and one for air (2 mL per stroke), absorbers for CO₂ and O₂, a hermetic nutrient solution container for the initial wetting of the plant substrate, a lamp for providing at least 200 μM*m^-2 *s^-1 PAR, and an automatic camera. The entire cuvette system is enclosed in a gastight and thermostatted containment. The electronics for control, time-lining and data logging are housed in a separate box. The plants are cultivated in a block of organic foam, being wetted at the beginning of a trial with a metered amount of nutrient solution. Subsequently, the moisture content is maintained constant by guiding the condensate into the block of foam. The seed is positioned and fixed into “plugs”. This work is accompanied by investigations on the optimization of the protocol for fast germinating and growing crop plants, primarily radishes, but cucumbers too.