Calibration of the Minolta SPAD-502 leaf chlorophyll meter

John Markwell, John C. Osterman, Jennifer L. Mitchell

Research output: Contribution to journalArticlepeer-review

564 Scopus citations


Use of leaf meters to provide an instantaneous assessment of leaf chlorophyll has become common, but calibration of meter output into direct units of leaf chlorophyll concentration has been difficult and an understanding of the relationship between these two parameters has remained elusive. We examined the correlation of soybean (Glycine max) and maize (Zea mays L.) leaf chlorophyll concentration, as measured by organic extraction and spectrophotometric analysis, with output (M) of the Minolta SPAD-502 leaf chlorophyll meter. The relationship is non-linear and can be described by the equation chlorophyll (μmol m-2)=10(M0.265), r2=0.94. Use of such an exponential equation is theoretically justified and forces a more appropriate fit to a limited data set than polynomial equations. The exact relationship will vary from meter to meter, but will be similar and can be readily determined by empirical methods. The ability to rapidly determine leaf chlorophyll concentrations by use of the calibration method reported herein should be useful in studies on photosynthesis and crop physiology.

Original languageEnglish (US)
Pages (from-to)467-472
Number of pages6
JournalPhotosynthesis Research
Issue number3
StatePublished - Jan 1995


  • Minolta SPAD-502 meter
  • chlorophyll
  • leaf meter

ASJC Scopus subject areas

  • Biochemistry
  • Plant Science
  • Cell Biology


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