Browsing by Author "Ranathunga, M.A.B."

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    Bio-Chemical Evaluation of Selected Sri Lankan Tea (Camellia sinensis L.) Cultivars and Accessions for Production of Green Tea
    (Faculty of Graduate Studies, University of Kelaniya, 2015) Ranasinghe, H.P.P.; Rajathewa, R.M.A.S.N.; Kottawa-Arachchi, J.D.; Ranathunga, M.A.B.; Amarakoon, A.M.T.
    Two major types of tea, ―green tea‖ and ―black tea‖ are produced from the young shoots of Camellia sinensis L. employing different processing methods. Sri Lanka traditionally produces black tea and the existing cultivars are more suitable for black tea production. However, due to the increased demand for green tea in certain countries, it could be economically advantageous for some Sri Lankan factories to produce green tea for niche markets. Therefore, this study was conducted to evaluate the potential of using selected Sri Lankan tea cultivars and accessions for the production of green tea. Tender shoots (two leaves and the bud) from 35 cultivars/accessions from St. Coombs Estate, Tea Research Institute of Sri Lanka, Talawakelle were steamed and dried to obtain green tea samples. Total polyphenol, catechin, free amino acid and caffeine content were determined by UV-vis spectrophotometric methods. Crude fiber content was determined according to ISO 5498. Three Chinese green tea samples were used as the controls. Crude fiber content was found to be < 16.5 %. Total polyphenol and catechin were found to be in the range of 9.55-26.19 % and 7.91-20.07 % respectively, while free amino acids and caffeine were found in the range of 0.83-5.31 % and 3.98-7.60 % respectively. According to the correlation matrix of different bio-chemical parameters, positive correlation was identified between catechin and total polyphenol content. Besides total polyphenol content had a significant negative correlation with amino acid content. Principal Component Analysis (PCA) revealed that, total polyphenols, amino acids and catechins are the main contributing characters. Based on the first three PCs, analyzed tea samples clustered into three main groups at an average distance of about 1.00. The group I comprised of fourteen cultivars/accessions. Eight cultivars/accessions were included in group II whereas group three represented sixteen cultivars/accessions. Comparatively high amino acid content (1.72- 5.06%), low total polyphenol (9.55-18.30%) and caffeine (4.08-5.80%) of cultivars/accessions in group II (CY 9, TRI 62/5, WHMOR, TRI 4079, PLLG 2 and DN) warrants them to be considered as potential cultivars/accessions for green tea production.
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    Correlation between selected morphological and biochemical parameters in a hybrid tea population with the blister blight disease
    (Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Weerasooriya, C.R.; Kottawaarachchi, J.D.; Ranathunga, M.A.B.; Amarakoon, A.M.T.
    Tea is produced from the plant species Camellia sinensis. Blister blight is a major leaf disease caused by the fungus Exobasidium vexans in tea resulting in significant yield losses, debilitation and death of tea bushes . Copper and systemic fungicides are currently used to control the disease resulting in high costs and potential residues in tea. In addition, there is a possibility of developing fungi resistance in tea plants to fungicides. Therefore, developing cultivars with resistance towards Blister blight is considered as the most suitable approach to control the disease. In the present study, the correlation between morphological and biochemical parameters was investigated with Blister blight disease with an aim to develop resistant cultivars. Twenty (20) tea samples including 18 accessions produced by crossing two parent cultivars: TRI 2043 (highly resistant to Blister blight) and TRI 3055 (highly susceptible to Blister blight) and the two parent cultivar samples were used in this study. The morphological analysis was carried out with reference to the guidelines given in the descriptors for tea by the International Plant Genetic Resources Institute (IPGRI) in 1997 and the descriptor list of the International Union for the Protection of New Varieties of Plants (UPOV) for tea (2008). Biochemical parameters were analysed following spectrophotometric methods and HPLC methods. Total anthocyanin, caffeine, polyphenol, gallic acid, epigallocatechin, catechin, epicatechin, epigallocatechin gallate and epicatechin gallate contents were determined. Results obtained for morphological and biochemical parameters were statistically analysed using the Minitab software under two categories; calculating the correlation between morphological and biochemical parameters and plotting a dendrogram for morphological and biochemical parameters separately. The Pearson correlation method was used to calculate the correlation between parameters. From the morphological parameters, a positive relationship was observed in the number of average pubescence on young leaf with the Blister blight resistance. Total anthocyanin content showed a positive relationship and epicatechin showed a low negative relationship with the Blister blight resistance. Accession 26 showed a very high total anthocyanin content (0.123 ± 0.065%), a moderate epicatechin content (0.792 ± 0.168%) and a high resistance to Blister blight disease, indicating its potential to be developed as a resistant cultivar. The experiment was duplicated, and the same results were obtained both times. Based on the results, it can be concluded that anthocyanin content can be suggested as a biochemical marker in tea crop improvement programs.