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Abstract The need to measure changes of chlorophyll concentration in citrus leaves required a nondestructive method of analysis applicable to field use. Light reflectance in the wavelength region of 600 nm had been shown to be useful for this purpose but existing reflectance meters were too bulky for field use and generally required line power. The instrument described here is battery operated, compact, and measures light reflectance in a band of wavelengths from 610 nm to 700 nm from four miniature incandescent lamps. Arrangement of the light unit on a spring clamp permits readings in the field on several leaves per minute. Calibration against measured chlorophyll concentrations yields a log log curve revealing maximum sensitivity at low chlorophyll concentrations. Tests on leaves from iron‐deficient orange trees showed the coefficient of variability to be in the vicinity of ± 15%. By reading 20 replicate leaves, sampling errors were compensated sufficiently to give precision of about ± 3%. Major limitations observed were (1) interference from red pigments in young leaves and (2) variable readings from mottled leaves, depending on position of the sensor on the leaf.
E. F. Wallihan (Sun,) studied this question.