THE USE OF CHEMICAL AND INFRARED SPECTRAL ANALYSES TO VERIFY THE IDENTIFICATION OF 2 SPECIES OF DUCKWEED, LEMNA-MINOR-L AND LEMNA-GIBBA L GROWN UNDER DEFINED CONDITIONS

Flat forms of the fronds of Lemna gibba L., used widely in laboratory experiments, can be easily confused with Lemna minor. Chemical analyses of the two species, grown under defined laboratory conditions, showed clear distinctions between the two species in relation to total protein content and the content of individual monosaccharides. Infra-red spectral analysis confirmed the chemical data for protein content and also revealed differences in the types of proteins present in the two species. Chemical and infra-red spectal analyses, particularly the amide I: carbohydrate absorbance ratio, provide a rapid and reliable means of verifying between the two species, which are often difficult to identify with certainty from morphological differences.