Eco-geographic and Genetic Variation among Populations of <em>Terminalia chebula</em> Retz. in Sri Lanka

Terminalia chebula Retz. (Aralu in Sinhala) is a perennial medicinal plant known for its vital medicinal properties and globally used in treating various health problems. Despite its significance, agronomic or ecological research on this species is limited compared to studies on its medicinal values. This research aimed to locate and identify the ecological distribution of T. chebula in different agro-ecological regions of Sri Lanka and to characterize different populations based on the morphological and genetic variation. Samples were collected from 125 T. chebula trees representing various populations, and 40 morphological characters were used for morphological characterization. Data were analyzed using principal component analysis and cluster analysis using the SAS statistical software. Genetic characterization was conducted through base sequencing at rbcL region of the genome. Results indicated that T. chebula populations in Sri Lanka can be clustered into four groups based on their morphological characters. Each group consists of plants from different locations, suggesting that grouping is not based on geographic or environmental parameters, a finding collaborated by genetic characterization. However, 80% of the Nilgala population grouped in one cluster and all the natural T. chebula plants are located only in the intermediate zone, indicated a relationship between environmental parameters and the species under natural conditions. Conversely, planted trees are found across all agro-climatic zones of Sri Lanka. Further, this study discussed the implications of these on the conservation, expansion of cultivation and effective utilization of T. chebula.