Bench-top Spectrophotometer CM-3700A


The SPAD-502Plus is a portable, non destructive measuring device for the chlorophyll content of leaves widely used to optimise the timing and quantity of fertiliser to improve crop yields.

Bench-top Spectrophotometer CM-3700A

Non-destructive measurement of plant chlorophyll

The SPAD-502Plus enables quick, easy measurement of the chlorophyll content of plant leaves without damaging the leaf. Chlorophyll content is one indicator of plant health and can be used to optimise the timing and quantity of applying additional fertilizer to provide larger crop yields of higher quality with lower environmental load.


Principal Applications

Monitoring of growth and health of plants

The SPAD-502Plus can be used to monitor the growth and health status of a wide variety of agricultural products, including wheat, rice, corn, cotton, etc.


Nitrogen fertilization optimization

The SPAD-502Plus can be used for determining when and how much nitrogen fertilizer should be provided to plants. Optimizing fertilization in this way leads to not only greater yields of higher quality, but also results in less over-fertilization, reducing environmental contamination due to the leaching of excess fertilizer into the soil and underground water.


  • Simple non-destructive measurements: measurements are taken simply by briefly closing the leaf inside the sensor. If necessary the same leaf can be used each time the measurement is made.
  • Monitor the nutritional health of crops: SPAD values are proportional to the amount of nitrogen in the leaf so by using regular SPAD readings and trend data, feeding can be optimised.
  • Small measuring area: the sensor of the SPAD-502Plus is only 2x3mm, suitable for even small or narrow leaves.
  • Water-resistant (IPX-4): can safely be used outside in wet and rainy conditions (should not be immersed in water).

Specifications & Downloads

Specifications & Downloads
Type Chlorophyll Meter SPAD-502Plus
Measurement subject Crop leaves
Measurement method Optical density difference at 2 wavelengths
Measurement area 2 mm × 3 mm
Subject thickness 1.2 mm maximum
Subject insertion depth 12 mm (with stopper having position adjustable from 0 to 6 mm)
Light source 2 LED elements
Receptor 1 SPD (silicon photodiode)
Display LCD panel showing 4-digit measurement value (values shown to first decimal place) and 2-digit number of measurements; Trend graph of values in memory can also be shown.
Display range -9.9 to 199.9 SPAD units
Memory function Memory capacity for up to 30 values; Calculation/display of average of data in memory also possible
Power source 2 AA-size alkaline batteries
Battery life More than 20,000 measurements (when using new alkaline batteries under Konica Minolta test conditions)
Minimum interval between measurements Approx. 2 seconds
Accuracy Within ±1.0 SPAD units (for SPAD value between 0.0 and 50.0 under normal temperature/humidity) “*” added to display when measurement exceeds 50.0 SPAD units
Repeatability Within ±0.3 SPAD units For SPAD value between 0.0 and 50.0 (with no change in sample position)
Reproducibility Within ±0.5 SPAD units
Temperature drift Within ±0.04 SPAD units/°C
Operating temperature/humidity range 0 to 50°C; Relative humidity of 85% or less (at 35°C) with no condensation
Storage temperature/humidity range -20 to 55°C; Relative humidity of 85% or less (at 35°C) with no condensation
Size; Weight 78(W)×164(H)×49(D)mm、200g(excluding batteries
Other Warning buzzer; User compensation factor
Standard accessories Depth stop; Strap; 2 AA-size alkaline batteries; Soft case; Reading checker
Specifications and appearance subject to change without notice. Company names and product names herein are trademarks or registered trademarks of their respective companies.

SPAD-502Plus Catalogue

Growth of rice plants and other agricultural products


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