Browsing by Author "Perera, S.A.C.N."

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    Assessment of the Diversity in Fruit Yield and Fruit Components among Sri Lanka Tall Coconut Accessions Conserved Ex-Situ
    (2015) Perera, K.N.S.; Herath, H.M.N.B.; Attanayaka, D.P.S.T.G.; Perera, S.A.C.N.
    Characterization of conserved coconut germplasm has been undertaken globally for identification of important features of different accessions for them to be effectively used in coconut breeding. One hundred and fifty seven accessions comprising of local and exotic material have been conserved in ex-situ field gene banks of Coconut Research Institute in Sri Lanka. The objective of this study is to quantitatively characterize nut yield and fruit components by weights among Sri Lanka Tall (Typica) coconut accessions. Twenty local tall coconut accessions were characterized for nut yield and fruit components following Bioversity International descriptors for coconut. Bunch wise nut yield was recorded in all the coconut phenotypes in the six most mature bunches in 25 randomly selected palms from each accession. Sampled nuts were scored for weights of fresh nut, husked nut, split nut and kernel and the weights ofhusk, water and shell ofeach nut were derived from the scored data. Analysis of variance by general linear models procedure and mean separation by Duncan's multiple range test were performed in SAS v8 and principal component analysis and cluster analysis using squared Euclidean distances were performed in Minitab VI7. General linear models procedure revealed significant differences for nut yield and all the fruit components at 5% probability level. Walahapitiya recorded the highest average nut yield followed by the Razeena with statistically equal performances. Clovis recorded the highest values for most of the parameters for fruit component analysis followed by the accession Margaret, grouping together in Dendogram and the scatter plot. The highest per nut kernel producer, Clovis, was followed by Margaret with statistically equal performances and this is important because kernel is the main economically important component followed by the husk. Results revealed that there is no significant correlation between nut yield and all the fruit components in tall accessions indicating the importance of taking these two parameters separately to formulate germplasm conservation strategies.
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    Charecterization of conserved coconut germplasm in srilanka with morphological descriptors
    (2009) Perera, S.A.C.N.; Ekanayake, G.K.; Attanayake, R.B.
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    Detection of Weligama Coconut Leaf Wilt Disease Phytoplasma by Real-Time Polymerase Chain Reaction
    (2020) Wijesekara, H.T.R.; Perera, S.A.C.N.; Bandupriya, D; Meegahakumbura, M.K; Lalith Perera
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    Evaluation of Coconut Germplasm in Weligama and Matara area of the Southern Province of Sri Lanka for Resistance to Weligama Coconut Leaf Wilt Disease
    (2015-06) Perera, S.A.C.N.; Herath, H.M.N.B.; Wijesekera, H.T.R.; Subhathma, W.G.R.; Weerakkody, W.A.T.L.
    Weligama Coconut Leaf Wilt Disease has been reported to infect the coconut palms in Southern Sri Lanka. Intra-cellular pathogen phytoplasma has been identified as the causal organism of this disease. So far there have been no known control methods to cure diseases caused by intra-cellular pathogens. Integration of resistant varieties into management programmes has been identified as a viable option in management strategies of such diseases. For this, it is essential to identify the resistance of available genetic resources. This study was carried out in the Weligama and Matara area of Southern Sri Lanka to screen the coconut germplasm for resistance to Weligama Coconut LeafWilt Disease. Infected and healthy palms were differentiated using symptomatology; flaccidity ofleaves, yellowing ofleaves and marginal necrosis of leaflets. Sri Lanka Tall, Sri Lanka Green and yellow dwarfs, Gon thembili tall and king coconut were among the main coconut fonns studied. Out ofthem Sri Lanka Green Dwarf recorded a high level ofresistance (98%). Within the Sri Lanka Yellow dwarf and Gon thembili tall, certain individual genotypes were observed to be resistant while king coconut was identified to be susceptible. The most popular commercial coconut variety, Sri Lanka tall was highly susceptible to the disease although there were certain individual genotypes which were resistant. Although Sri Lanka Green dwarf has not so far been viable as a commercial coconut cultivar the presence of resistant genes within the coconut gennplasm was recognized as a great advantage in breeding coconuts for resistance to Weligama Coconut Leaf Wilt Disease.
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    In Vitro Characterization of Indigeneous Coconut Varieties (Cocos nucifera L.) of Sri Lanka for Water Stress Tolerance
    (2012) Fernando, S.C.; Santha, E.S.; Perera, S.A.C.N.; Dissanayake, H.D.M.A.C.; Meegahakumbura, M.G.M.K.; Perera, L.
    Coconuts show a remarkable yield drop due to long dry periods caused by global climatic changes.Thus, breeding for drought tolerance has become a priority in coconut breeding in Sri Lanka.Five coconut varieties indigenous to Sri Lanka, namely Ran thembili,Gon thembili, Porapol, Bodiri and Red dwarf were screened for their drought tolerance potential in vitro. Mature zygotic embryos collected from self pollinated nuts of each variety were germinated and developed into plants with one photosynthetic leaf in Y3 medium.Water stress condition was induced by application of Polyethylene Glycol(PEG) into the culture medium.The level of PEG in culture medium was gradually increased from 2% to 7% until the plants showed water stress symptoms in leaves; yellowing and necrosis.More than 75% of zygotic embryos of all tested coconut varieties successfully gemJinated in vitro and developed into plants. Plants of all tested coconut varieties survived water stress caused by 4% to 6% PEG and the percentages of plant survival at different levels of PEG varied among different coconut varieties. Variety Ran thembili showed the highest survival rate(27%) at 6% PEG and overall best plant growth perfomJances at 4% PEG among the five coconut varieties tested. Red dwarf showed the lowest survival rate at 4% to 6% PEG indicating its susceptibility to water stress. Among the coconut varieties tested, zygotic embryos of Ran thembili showed the highest drought tolerance potential.
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    An Investigation of the Tender Nut Potential of Diverse Coconut (Cocos nucifera L.) Varieties/Forms in Sri Lanka
    (2015) Perera, S.A.C.N.; Ekanayake, G.K.; Herath, H.M.N.B.
    There is a rising demand in the world for coconut water as a healthy natural beverage. Different coconut varieties are used in different countries to be processed as a natural drink. The coconut form "King coconut" has long been used in Sri Lanka as the ideal coconut variety for this purpose. However, with the expansion in the local and export beverage coconut market, the supply does not meet with the demand at present. Therefore, this study was conducted to identify potential coconut varieties/forms mainly relating to the yield of beverage. The study was conducted in the main coconut triangle and Southern Sri Lanka. Eleven coconut forms, namely, King coconut and Bothal thembili in the variety Aurantiaca, Red, Yellow, Green and Brown dwarf and Murusi in the variety N ana, Bodiri, Dothal u, and Sri Lanka tall. These are included in the variety Typica along with NipoJ, which is a natural hybrid being identified to be suitable as beverage coconuts. Out of them the yielding ability was high in King coconut, Red dwarf and Yellow dwarf while Bodiri, Nipol and Dothalu fared well. Many coconut forms suitable for beverage purpose were observed to be having seasonality in nut production. Ensuring adequate soil fertility and prevention of water deficit over prolonged periods were observed to help sustain yield and reduce seasonality in bunch emission. There were no large scale plantations for beverage coconuts in Sri Lanka, and the entire collection was from home gardens and very small scale holdings. It is recommended to establish medium scale holdings with coconut forms having high yield potential as identified in the current study, with proper management guidance to ensure a steady supply of beverage coconuts to the local as well as export market.
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    Varietal Classification of New Coconut (COCOS nucifera L) Forms Identified from Southern Sri Lanka
    (2010) Ekanayake, G.K.; Perera, S.A.C.N.; Dassanayake, P.N.; Everard, J.M.D.T.
    Coconut in Sri Lanka is currently classified into 15 different coconut forms grouped under three varieties, namely Typica, Nana and Aurantiaca. Several new coconut morphotypes that were not represented in the previous classifications were identified during a recent coconut germplasm exploration mission in the Southern Province of Sri Lanka. The visual morphological features of several new coconut morphotypes (Ran pol, Bothal thembili, Juwan, Murusi, Dothalu and Thatin) were characterized with the objective of including them in the taxonomic classification of coconut in Sri Lanka. Stature and breeding behaviour were the main features observed while stem morphology, root bole formation, crown size, nut morphology and bearing patterns, and other specific morphological features were recorded. The data provided morphological evidence to classify Ran pol, Juwan and Rath gon thembili as new forms of variety Typica; Green dwarf 'Murusi', Yellow dwarf 'Murusi' and Brown dwarf 'Murusi' as forms of variety Nana; and Bothal thembili as a new form of variety Aurantiaca. The morphotypes, Thatin and Dothalu were identified as forms of variety Typica but the sample size was too small for confirmation.