EARS miniPPM-300 Plant Photosynthesis Meter

The EARS miniPPM is the third generation of the Plant Photosynthesis Meter developed by EARS Plant Photosynthesis Monitoring B.V. (EARS-P2M), AgroCares’ sister company in Wageningen. It is a handheld, modulated saturation-pulse fluorometer: it uses the chlorophyll fluorescence signal of a leaf to measure how efficiently the plant is photosynthesising.

The instrument is simple to operate: press the button and a photosynthesis measurement is completed within a second. Laboratory tests show stable, reproducible measurements. Innovations in optics and electronics made the device much smaller and lighter than earlier versions without compromising on accuracy: it weighs 250 grams and does about 3,000 measurements on a full battery.

What the miniPPM-300 measures

Everything the smaller models do, plus photosynthetically active radiation (PAR), photosynthesis rate in ambient light (P), long unattended measuring series, photosynthesis at pre-defined light levels and fully automatic light-photosynthesis curves. Measurements are stored with date and time in the instrument, on microSD card or downloaded to a PC over USB, and the instrument can be controlled from the PC.

Steering the light climate in greenhouses

Plants can be damaged by too much light. The miniPPM-300 measures the photosynthesis light curve of a crop automatically, so growers know exactly at which light level to start screening. In the EARS example the optimum occurs at 780 µmol/m²s, while PAR levels in greenhouses on sunny days can reach 1,700 µmol/m²s.

Application areas

The miniPPM is used in research, education and horticultural practice: herbicide efficacy and damage assessment, quality of plants, vegetables and fruit, seedling screening for breeding and monitoring of plant photosynthesis yield. Growers use it to see when light screening is needed: as a rule of thumb, screening is necessary when the photosynthesis yield drops below 40%. The 300 is also used for plant photosynthesis rate monitoring, steering of the light climate in greenhouses and irrigation management.