This study was conducted to determine the effects of soil and climatic conditions on glycyrrhizic acid contents in various Iranian populations of Glycyrrhiza glabra in two root diameters. Twelve populations in arid, semi-arid and Mediterranean climates of different parts of Iran were collected and the content of glycyrrhizic acid was determined using HPLC. The results showed that contents of glycyrrhizic acid varied in roots with different diameters. Average contents of glycyrrhizic acid varied 1.36-3.40% in the studied populations. These changes were not significantly correlated to edaphic parameters, but were significantly influenced by temperature. Cluster analysis of twelve populations of licorice plants regarding glycyrrhizin content categorized these populations in three groups. There was little correlation between glycyrrhizin content and climatic classification, and this reveals that glycyrrhizic content is more affected by genetic factors rather than environmental conditions; therefore, selection of studied liquorices population with high glycyrrhizic acid content would be useful for their genetic improvement.

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