Our research aimed to study the correlation between the SPAD-502 readings and the color space CIE L*a*b* values in two cultivars of Alstroemeria sp. during leaf senescence and to evaluate the statistical criteria used in the selection of the best fit calibration functions. We demonstrate the importance of the Akaike information criterion and the parsimonious function besides the coefficient of determination. The reliability of the functions was tested by Student's t-test comparison between the chlorophyll (Chl) estimated from SPAD readings and their chemical concentrations. Polynomial and Hoerl function described well the changes in Chl a and total Chl (a+b) during senescence, but calibration functions are required to perform for each cultivar. We demonstrated that CIE L*a*b* system is reliable to estimate SPAD reading at stages of leaf senescence of Alstroemeria sp. and can be used instead of SPAD-502.