Graduate Studies

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Author: search.filters.author.Rajapakse, S.

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    Interspecific Relationships of Piper Species in Sri Lanka as Revealed by DNA Barcode ITS
    (Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Jayarathna, N.; Senanayake, S.P.; Rajapakse, S.; Jayasekera, R.; Paranagama, P.A.
    The genus Piper which is the largest genus in the family Piperaceae is economically important as it comprises with valuable crop species as well as several wild species. Although ten species of genus Piper are recorded in Sri Lanka, their interspecific relationships were not well studied. Therefore, the aim of this study was to determine interspecific relationships of Piper species in Sri Lanka using internal transcribed spacers from nuclear ribosomal DNA )ITS(. Ten varieties of Piper nigrum L., two varieties of each P. betle L.and P. longum L., P. chuvya )Miq.( C. DC., P. siriboa L., P. sylvestre Lam., P. walkeri Miq. and P. zeylanicum Miq. were used for the study. The genomic DNA was extracted from tender leaf samples using CTAB method, PCR amplified using ITS primer pair and subjected to DNA sequencing. The DNA sequence alignment analysis was carried out and a dendrogram was constructed using the multiple sequence alignment programme MUSCLE. According to the dendrogram clear formation of two major clusters can be seen and ten P. nigrum varieties were clustered together however, variety Kuching has shown a separation from the main cluster. P. longum, P. walkeri, P. sylvestre, P. siriboa, P. betle, P. chuvya and P. zeylanicum formed the other cluster in which P. siriboa has shared close similarities with P. betle, while P. sylvestre and P. walkeri displayed close relationships and clustered together with P. longum varieties. Interspecific relationships between wild species and cultivated species )P. nigrum, P. betle and P. longum( indicated the potential of using the wild species in breeding programs for crop improvement. However, further studies to reveal genetic and phenetic relatedness of those species are needed to deepen the knowledge on interspecific relationships of Piper species.
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    Sri Lankan research output in the global context: Where do we stand?
    (University of Kelaniya, 2013) de Silva, N.L.; Wijetunga, P.; Rajapakse, S.
    Introduction and objectives: There is little data on the contribution to global research by Sri Lankan researchers. We studied the research performance by Sri Lankan researchers with the objectives of describing publication patterns and principal subject areas, identifying key research institutions and international collaborations, assessing the evolution of research patterns and the level of citations. Methods: We searched several key databases for publications with Sri Lankan authors from 2003 to 2012. Retrieved data were categorised as ‘peer-reviewed journal papers’ and ‘conference presentations’, and analysed according to document type, subject area, institution, journal, international collaborations, and citation details. Results: The total number of publications was as follows: 4777 from Web of Science (WoS), 6546 from Scopus, 2212 from EMBASE, 1684 from Medline 2789 from CABdirect and 462 from IEEEXplore. Majority were articles. From 2003 to 2013, the number of peer reviewed journal papers has gradually increased, while the number of conference abstracts has declined. The Universities of Peradeniya (WoS-26.8%, Scopus-23.53%), Colombo (WoS-18.3%, Scopus-19.95%) and Kelaniya (WoS-8.5%, Scopus-8.53%) had the highest output. In WoS the above three institutions had h-indices of 37, 33 and 24 respectively while values for Scopus were 40, 37 and 25. The highest number of publications was in the field of medicine. The highest numbers of international collaborations were with USA in WoS (13.7%) and UK in Scopus (13.94%). Contributions to global output in WoS were 0.036% and in Scopus 0.035%. Conclusion: Publications by Sri Lankan authors in peer-reviewed journals are increasing, but the contribution to global research remains low. Policy makers should support academic institutions to enhance the quality, relevance and output of research by Sri Lankan researchers, and researchers should focus on obtaining high quality publications.