Tropical Agricultural Research Vol. 20: 193 - 199 (2008) Identification of Discriminating Morphological Descriptors for Characterization of Tea (Camellia sinensis L.) Germplasm in Sri Lanka J.H.N. Piyasundara, M.T.K. Gunasekare 1 and I.P. Wickramasinghe 2 Division of Plant Breeding Tea Research Institute Talawakelle, Sri Lanka ABSTRACT. Accessibility of germplasm in breeding programs depends largely on the availability of characterization and evaluation data. Tea germplasm accessions conserved in the ex situ gene bank at Tea Research Institute, have not been characterized systematically to identify morphological markers contributing to phenotypic variation of the local germplasm. Therefore, rationalizing the list of proposed descriptors to identify the most discriminating descriptors relevant for local tea germplasm is a prerequisite for efficient characterization. The present study was undertaken to find out highly discriminating morphological descriptors contributing to the variation in the local tea germplasm through multivariate statistical techniques. Two hundred and three germplasm accessions conserved in the ex situ gene bank collection was characterized using 20 standardized morphological descriptors. Principle Component Analysis (PCA) using 20 descriptors showed that 16 out of 20 descriptors were informative and contributes significantly to the variation present in the germplasm. Cluster analysis based on significant principle components further revealed that descriptors viz. type of serration of leaf margin, waviness of the leaf margin, pigmentations in young leaf, pigmentations in leaf petiole, size of the leaf and leaf angle were the most discriminating descriptors in distinguishing accessions into phenotypically diverse groups. The present study identifies the morphological descriptors that are most relevant for characterization of tea germplasm in Sri Lanka. INTRODUCTION The importance of using genetic resources in breeding programs to enhance crop genetic potential has been well recognized (Thomas and Mathur, 1991). However, the accessibility of the germplasm depends largely on the information available on characterization and evaluation. Use of morphological characters is cost effective when compared to the use of biochemical and molecular markers for preliminary characterization of large number of accession to identify morphologically similar groups and for simple varietal identification of phenotypically distinguishable cultivars (Martinez et al., 2003). Among the several activities, the first step for proper characterization of germplasm is to identify the phenotypic variation present in the given germplasm. In order to achieve this objective, the germplasm accessions need to be characterized using a standard set of descriptors. A descriptor list for 1 Division of Plant Breeding, Tea Research Institute of Sri Lanka. 2 Department of Agricultural Biology, Faculty of Agriculture, University of Peradeniya, Peradeniya, Sri Lanka.