Comparison and Standardization among Chlorophyll Meters in their Readings on Rice Leaves

Six chlorophyll meters (SPAD) were compared to determine the magnitude of differences in SPAD readings on rice leaves. Correlations among the six SPAD meters were statistically significant (P<0.01) with correlation coefficients (r) ranging from 0.971 to 0.990. However, the differences in SPAD readings were statistically significant among the six meters (P<0.05) and the difference between two meters was as large as 2.7 units. Such magnitudes of discrepancy should be considered when different SPAD meters are used in the same study.