Browsing by Author "Kottawa-Arachchi, J.D."

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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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    Molecular characterization of Sri Lankan tea [Camellia sinensis (L.) O. Kuntze] genotypes with diverse origins using SSR markers for future breeding programmes
    (Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Kottawa-Arachchi, J.D.; Ranathunga, M. A. B.; Sharma, R. K.; Amarakoon, A. M. T; Gunasekare, M. T. K.; Chaudhary, H. K.; Attanayake, R. N.
    The tea plant [Camellia sinensis (L.) O. Kuntze] is one of the most popular non-alcoholic beverage crops worldwide. Tea germplasm is the most valuable and fundamental resource for breeding high yielding, climate resilient, and quality tea cultivars. Therefore, efforts were made to characterize the existing genetic diversity of Sri Lankan tea using simple sequence repeat (SSR) markers. A total of 91 tea accessions including exotic, estate selections, improved quality and diverse cultivars were selected for the diversity estimations. Eleven informative highly polymorphic SSR markers selected based on inferences of previous studies (EST, miRNA and traits associated SSR markers) were used in this study. Genetic relationships were analyzed by a neighbor-joining (NJ) tree constructed using DARwin software. Genetic structure analysis was performed by the Bayesian clustering model using STRUCTURE analysis and the optimum delta K was generated. Genetic diversity analysis grouped all the accessions into three major clusters. Further, structure analysis complemented the cluster analysis and revealed three genetic populations (China types with Korean origins, Assam types with ASM4/10 ancestral relationship and mixture of different origins) in the Sri Lankan tea germplasm. Newly recommended TRI5001, TRI5002, TRI5003 and TRI5004 cultivars have shown affinities with five Assam introductions and grouped together in the same cluster. Interestingly, five high yielding TRI developed cultivars (TRI2023, TRI2025, TRI3013, TRI3055 and TRI3073) having an ancestral relationship with the parent ASM4/10 were also grouped together. Likewise, seven accessions of Azerbaijan origin were remained together. The estate selections were scattered in the three clusters. The inferences of the current study provide molecular evidence for the genetic diversity and population structuring of the tea germpalsm and will help the selection of the potential parental group for the future cultivar development programme of Sri Lanka.