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

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    Optimization of a Somatic Embryogenesis Protocol from Nodal Cuttings and Leaf Explants of Camellia sinensis (L.) O. Kuntze
    (Uva Wellassa University of Sri Lanka, 2020) Gunathilake, M.A.S.; Ranaweera, K.K.; Ranatunga, M.A.B.; Alwis, L.M.H.R.
    Tea is the main agricultural foreign exchange earner in Sri Lanka. Tea is commonly propagated by vegetative cuttings; the mostly adopted practice commercially, thus unable to fulfill the annual planting material requirements. Somatic embryogenesis (se) is considered as a rapid mass propagation method in woody perennials; however, in tea, potential has not been explored yet. This study was aimed to identify optimum growth regulator combinations to produce embryogenic calli from nodal cuttings and leaves of tea and to identify optimum conditions for somatic embryo induction from leaf calli. Sterilized field-grown explants viz nodal cuttings and leaf segments of TRI 2025, TRI 2043, and leaf calli of TRI 2043 were established on solid MS media with different plant growth regulator combinations under aseptic conditions. Ten replicates were used for a growth regulator combination and callus initiation was visually observed at weekly intervals. Initiated calli were qualitatively rated for callus mass. The highest callusing of nodal cuttings was observed in MS medium contained 0.11 mg L-1 TDZ, 0.1 mg L-1 IBA, 3 mg L-1 GA3, 8.6 mg L-1 AgNO3 for TRI 2025 while MS media contained 0.11 mg L-1 TDZ, 0.1 mg L-1 IBA, 3 mg L-1 GA3 was reported as the best for TRI 2043. The highest calli induction from leaves was observed in MS medium contained 0.11 mg L-1 TDZ, 1.86 mg L-1 NAA for TRI 2025, and MS medium contained 0.0044 mg L-1 TDZ, 0.1 mg L-1 IBA, 3 mg L-1 GA3 for TRI 2043. Meanwhile, results showed that early signs of somatic embryo induction in solid MS medium containing 0.044 mg L-1 TDZ, 0.1 mg L-1 IBA, and 3 mg L-1 GA3 for leaf callus of TRI 2043. Among two cultivars, TRI 2025 showed a high response for calli initiation with higher callus mass in both nodal and leaf explants than TRI 2043. Identified combinations can be used to obtain embryogenic calli from nodal cuttings and leaf explants and results provide a foundation for developing a se protocol for tea. Keywords: Tea, Explant, Somatic embryogenesis, embryonic callus.
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    Screening of Tea Germplasm on Suitability for Green Tea Manufacturing
    (Uva Wellassa University of Sri Lanka, 2016) Abesinghe, A.H. M. G. I.; Alwis, L.M.H.R.; Kahandage, K.P.M.; Ranatunga, M.A.B.
    Demand for green tea consumption has gone up among the local consumers. Thus, tea growers look for cultivars suitable for green tea production. Studies were conducted to screen the suitability oftea germplasm for green tea manufacturing aiming for developing better cultivars in future. Twenty six accessions from the germplasm representing exotic collection, recommended cultivars and estate selections were used. Two leaves and the bud were picked from plants and green tea was prepared using an optimized hand processing method by steaming to deactivate enzymes, hand rolling and pan frying, twisting and drying. Samples were triplicated and sensory evaluation on quality of ungraded green tea was done by professional tea tasters. Taster's comments were transformed into ranks and scores were summed up to get the Total Quality Score (TQS). Ranked data were subjected to cluster analysis using Average Distance Cluster method and resultant dendrogram was constructed using PAST 3 software. Twenty six accessions were grouped based on the average ratings given for individual quality parameters; dry leaf:, appearance, aroma, infused leaf: appearance, aroma, liquor: appearance, aroma, colour, taste using average linkage cluster analysis. Resultant dendrogram was clustered in to four major groups. First group comprised of CH13, estate selection and six accessions from the exotic germplasm collection. All those accessions were rated as producing high quality green tea. The second group consisted of TRI 4067 recommended cultivar and six other accessions from the exotic germplasm collection, which are also considered as good accessions for quality green tea. This is the first attempt on screening tea germplasm for developing a Sri Lankan green tea cultivar. Keywords: Green tea, Sensory evaluation, Exotic tea germplasm, Polyphenol, Caffeine
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    Somatic Embryo Induction from in vitro Leaf Callus of Tea [Camellia sinensis (L.) O. Kuntze] Cultivars, ‘TRI2024’ and ‘TRI2043’
    (Uva Wellassa University of Sri Lanka, 2018) Sukirtharubani, S.; Ranaweera, K.K.; Ranatunga, M.A.B.; Thirukkumaran, G.
    Tea [Camellia sinensis (L.) O. Kuntze] is a major plantation crop that plays a key role in the economy of Sri Lanka. Thus, the aim of this study was to improve the indirect somatic embryogenesis and initiate embryogenic callus formation in tea. The explants of green colour compact in vitro leaf callus of TRI2024 and TRI2043 cultivars were cultured on the solid and in liquid MS media containing different plant growth regulators to induce the embryogenic callus under in vitro condition. The three factorial CRD with cultivar, treatment and media formulation as factors were used as the experimental design with ten replicates for each treatments. The highest average relative growth rate (82.3%) was occurred in leaf callus of TRI2024 cultivar on MS solid medium supplemented with 2 mg 1- BAP + 3 mg l- NAA. The highest average growth index (17.6) was occurred in leaf callus of TRI2024 cultivar on MS solid medium supplemented with 2mg/L BAP + 3 mg 1- NAA + 8.6 mg 1- AgNO3. However, the highest average relative growth rate and average growth index for callus of TRI2043 cultivar was observed in liquid media than solid media. Somatic embryo induction was initially observed on in vitro leaf callus of TRI2024 cultivar within ten weeks of culture. There is a significant difference between the cultivars, media and media formulations (solid and liquid) and interaction between cultivars in callus induction and proliferation. The MS solid medium containing 2 mg 1- BAP + 3 mg 1- NAA was reported as the best medium for indirect somatic embryogenesis from the in vitro leaf callus of tea cultivar TRI2024. This protocol with further extended experiments will be used to obtain embryogenic callus from in vitro leaf callus of tea. Therefore it will be beneficial for mass propagation of selected elite clones of tea in the future.