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Perera, S. A. C. N.
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Comparative Evaluation of Sri Lanka Tall and Dwarf x Tall Coconut Hybrids for Tolerance to Weligama Coconut Leaf Wilt Disease in Sri Lanka Perera, S. A. C. N.; Waidyarathne, K. P.; Dissanayaka, H. D. M. A. C.; Nainanayake, N. P. A. D.; Ekanayake, G. K.
International Coconut Community Journal Vol 32 No 2 (2016): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (405.394 KB) | DOI: 10.37833/cord.v32i2.30

Abstract

Weligama Coconut Leaf Wilt Disease (WCLWD) is a phytoplasma disease found in Southern Sri Lanka. It is an incurable, debilitating disease resulting in yield loss and ultimate death of the palm and over 250,000 palms have been identified to be infected. Breeding coconuts for resistance is a viable option in managing incurable diseases and for this WCLWD resistant germplasm is needed. Accordingly, the objective of the current research was to investigate the comparable levels of WCLWD resistance of Sri Lanka tall and CRIC65 coconut cultivars which are favoured in Sri Lanka. Eight coconut estates which were planted with Sri Lanka tall (SLT) and CRIC65 hybrids as a mixed plantation or in close proximity were observed. Out of them an extent of about 04 acres of one estate was selected for detailed analysis using the disease severity index developed based on the WCLWD symptoms; flaccidity, leaf yellowing and marginal necrosis of leaflets. General observations indicated the presence of WCLWD in both SLT and the hybrid CRIC65. Marginal necrosis was at a minimal level in both the cultivars, while the other symptoms; flaccidity and yellowing scored higher values at all levels in the spiral in SLT than in hybrid CRIC65. Moreover, the hybrid coconut CRIC65 displayed lower percentage of disease incidence and significant reduction in the levels of the main symptom flaccidity. As a result, the hybrid palms recorded significantly low disease index value than SLT. Moreover, disease incidence was observed to be low in properly managed estates irrespective of the cultivar. With the findings of the current study, coconut varieties SLGD and selected SLT which remain healthy under the same disease pressure can be recommended as parents in a breeding programme aiming at resistance/tolerance to WCLWD.
Assessment of the Diversity in Fruit Yield and Fruit Components among Sri Lanka Tall Coconut Accessions Conserved Ex-Situ Perera, K. N. S.; Herath, H. M. N. B.; Attanayaka, D. P. S. T. G.; Perera, S. A. C. N.
International Coconut Community Journal Vol 31 No 2 (2015): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (495.279 KB) | DOI: 10.37833/cord.v31i2.60

Abstract

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 genebanks 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 of husk, water and shell of each 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 V17. 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.
An Investigation of the Tender Nut Potential of Diverse Coconut (Cocos nucifera L.) Varieties/Forms in Sri Lanka Perera, S. A. C. N.; Ekanayake, G. K.; Herath, H. M. N. B.
International Coconut Community Journal Vol 31 No 1 (2015): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (303.049 KB) | DOI: 10.37833/cord.v31i1.69

Abstract

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 Nana, Bodiri, Dothalu, and Sri Lanka tall. These are included in the variety Typica along with Nipol, 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 andYellow 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.
In Vitro Characterization of Indigenous Coconut Varieties (Cocos nucifera L.) of Sri Lanka for Water Stress Tolerance Fernando, S. C.; Santha, E. S.; Perera, S. A. C. N.; Dissanayake, H. D. M. A. C.; Meegahakumbura, M. G. M. K.; Perera, Lalith
International Coconut Community Journal Vol 28 No 2 (2012): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (215.856 KB) | DOI: 10.37833/cord.v28i2.103

Abstract

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 germinated 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 performances 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.
Co-Authors Attanayaka, D. P. S. T. G. Dissanayaka, H. D. M. A. C. Dissanayake, H. D. M. A. C. Ekanayake, G. K. Fernando, S. C. Herath, H. M. N. B. Meegahakumbura, M. G. M. K. Nainanayake, N. P. A. D. Perera, K. N. S. Perera, Lalith Santha, E. S. Waidyarathne, K. P.