Z950 PRI Pen

The Z950 PRI-Pen is a hand-held, battery-powered PlantPen that measures leaf reflectance at 531 nm and 570 nm and calculates Photochemical Reflectance Index (PRI).  PRI is sensitive to changes in carotenoid pigments and these are indicative of changes in photosynthetic light use efficiency and the rate of CO2 uptake.  PRI is  a reliable plant water-stress index.

The Z950 PRI-Pen is a rugged and compact device. It can be used in the field, in the laboratory or the greenhouse.  A handy leaf clip, simple two-button operation, and a bright LCD display make this PlantPen easy to use.  PRI measurements are made noninvasively on intact plants (no leaf tearing or damaging).

The following versions of Z950 are available: Z950 – Standard with no data transfer Z950-USB with data transfer via USB and software, Z950-BT with data transfer via Bluetooth and software

It takes four AAA alkaline batteries and is supplied in a robust case. The memory of PRI-Pen has a capacity of 4 MB (up to 100,000 data points). Measured data are numbered and may be recalled in sequence for later transfer to a computer.

In addition to Z950 PRI-Pen we offer the Z951 NDVI-Pen, which measures the Normalized Difference Vegetation Index (NDVI) and Z955 N-Pen which measures NDGI ratio and calculates total N content or Z970 PolyPen that measures leaf reflectance at multiple wavelengths and caluclates multiple indices.  Contact us for more information.


  • Small hand-held instrument for leaf light reflectance measurements
  • Calculates PRI ratio
  • User friendly, two button operation
  • Available in standard, Bluetooth or USB version
  • comprehensive software package avilable or PC with BT or USB version