The portable chlorophyll (Chl) meter (CL-01, Hansatech) has been successfully used for a rapid and direct estimation of total Chl content in the leaves of some crops. We compared CL-01 meter readings (Chl value) and Chl contents in leaves of Zea mays, Cucumis sativus, Raphanus sativus, and Ceiba speciosa. Chl index was linearly and positively correlated to Chl content in all the species.Additional key words: Ceiba; Cucumis; Raphanus; Zea.---Plants contain chlorophylls (Chls) a and b. The two compounds have different solubilities in organic solvents, and somewhat different, though overlapping, electronic spectra in the visible region. Traditionally, chemical methods of determination have required Chl extraction by a solvent, followed by the spectrophotometric determination of absorbance by the Chl solution, and conversion from absorbance to concentration using standard equations (Arnon 1949, Lichtenthaler 1987, Ritchie 2008. In the standard method of Chl determination, extraction requires destructive sampling and is relatively time consuming (Richardson et al. 2002). More recently, non-destructive optical methods, based on the absorbance and/or reflectance of radiation by the intact leaf have been developed. Optical methods yield a 'Chl index' value that expresses relative Chl content but not absolute Chl content per unit leaf area or per mass of leaf tissue. These newer methods are non-destructive, very quick, and can be used in the field (Markwell et al. 1995, Hawkins et al. 2007.Many papers show the application of "Chl value" to the estimation of leaf Chl content (Richardson et al. 2002, Uddling et al. 2007), but some have failed to show the applicability of the index across different studies, plant species, or stresses. Neufeld et al. (2006) working with ozone-affected leaves of cutleaf coneflower (Rudbeckia laciniata var. digitata) observed that when relatively uninjured leaves were measured, SPAD meter readings were linearly related to total Chl content. However, when leaves with foliar injury were added, it was no longer possible to use the same equation to obtain Chl estimations for both classes of leaves.The objective of this work was to evaluate the existence of relation between the Chl content and "Chl value" measured by hand-held Chl meter CL-01 in maize (Zea mays), cucumber (Cucumis sativus), radish (Raphanus sativus), and floss-silk tree (Ceiba speciosa). Plants were grown from seed in a glasshouse. Approximately 50 leaf samples of the each species, spanning as wide a range of Chl contents as possible, from very pale yellow to very dark green leaves, were used. One hand-held Chl meter, the CL-01 (Hansatech, King's Lynn, Norfolk, England) was used. This equipment provides a convenient, low cost method of measuring the relative Chl content of a leaf sample using dual wavelength optical absorbance (620 and 940 nm) measurements from leaf samples. Five separate measurements were made on each leaf and we used the arithmetic mean of these measurements for all subsequent analyses, and the results were expres...