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Perera, Lalith
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The Most Frequent Agronomic Practices Used by the Coconut Farmers in the “Coconut Triangle” of Sri Lanka Legrand, Baptiste; Perraut, Angélique; Herath, Chaminda; Wijekoon, Rusitha; Perera, Lalith
International Coconut Community Journal Vol 34 No 2 (2018): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (268.772 KB) | DOI: 10.37833/cord.v34i2.18

Abstract

The study was carried out to identify the most frequently practiced cultural practices by coconut growers in the main coconut growing area termed as “Coconut Triangle”, among a set of technical practices recommended by the Coconut Research Institute of Sri Lanka (CRISL). The objective was also to analyse the impact of these practices to the yield and to analyse the effects of the information sources to the growers to enhance the farmers skills. The study was carried out between June 2018 and August 2018. For the data collection, a questionnaire developed by CRISL was used and 62 growers were randomly selected. All the answers were gathered in a table file. Then, the data were analysed using tabular analysis and the software SPSS. The study reveals that most of the growers are having intercrops between the coconut trees, in large or very small scale even if the yield is lowand needs more space. For the soil moisture conservation around the coconut palm, the majority of the growers use the simple and low-cost technique; mulching around the coconut palms. However, 30.1% of the growers were found to not use any technique to improve the soil moisture even when the drought is a frequent event in the country, but this more valid for small scale growers. To improve their yield, majority of the growers preferred and used CRISL recommended coconut fertilizer mixture (Adult Palm Mixture or APM) over the other commercially available fertilizer mixtures. Finally, the study shows that farmers with large estates are the most involved to follow training programs and apply the advices given by the CRISL.
Screening Coconut Cultivars for Tolerance to Infestation by the Coconut Mite, Aceria guerreronis (Keifer) in Sri Lanka Perera, Lalith; Sarathchandra, S. R.; Wickramananda, I. R.
International Coconut Community Journal Vol 29 No 1 (2013): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (155.563 KB) | DOI: 10.37833/cord.v29i1.97

Abstract

The coconut mite (Aceria guerreronis Keifer) is a tiny pest which severely damages the nuts of the coconut palm (Cocos nucifera Linnaeus). At present there is no appropriate control method for this pest in Sri Lanka. Field observations have revealed difference in the severity of A. guerreronis mite infestation among selected and improved coconut cultivars in Sri Lanka. This difference has not been studied in depth and therefore the present study was conducted to investigate the levels of tolerance in selected and improved coconut cultivars and, if differences were demonstrated, to understand the mechanism behind the tolerance. A replicated trial in Thammenna Estate (TE) in Puttalam district in Sri Lanka, where the mite infestation was natural and severe, was selected for this study. The trial was planted in 1983 and consisted of two improved coconut cultivars; Sri Lanka Yellow Dwarf x Sri Lanka Tall (YDT) and Sri Lanka Green Dwarf x Sri Lanka Tall (GDT) and the selected Sri Lanka Tall cultivar (TT) which has, green (TTG) and russet coloured (TTR) forms. Population assessment of mites on immature nuts, damage initiation of the fourth bunch and harvest records were obtained. Further, characters that were thought to influence tolerance, such as nut shape as measured by ratio of length to breadth, the tightness of perianth to the nut surface and some changes in the affected tissues were also recorded. Yield data were collected for each cultivar to estimate the crop loss due to coconut mite damage. The results revealed that out of the cultivars tested in this trial, YDT had the lowest incidence of mite colonization and the smallest mite population size and symptom initiation compared to others. The distance between the perianth and nut surface, the least in YDT, is suggested as the most probable morphological feature that would impart tolerance to mite infestation.
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.
Coconut Palms on the Edge of the Desert: Genetic Diversity of Cocos nucifera L. in Oman Perera, Lalith; Baudouin, Luc; Bourdeix, Roland; Fadhil, Anwar Bait; Hountondji, Fabien C. C.; Al-Shanfari, Abdulaziz
International Coconut Community Journal Vol 27 No 1 (2011): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (241.905 KB) | DOI: 10.37833/cord.v27i1.120

Abstract

In the Gulf region, coconuts are almost exclusively produced from palms growing in the Sultanate of Oman, particularly in the extreme south-eastern coastal plain of the Dhofar Governorate, and specifically within the city limits of Salalah, between the Jebel and the sea. The importance of these coconuts is not only agricultural; historically, the Dhofar palms provided the basic materials to build boats for fishermen and traders on, around and eventually beyond the Indian Ocean. Coconut palms are now one of the main symbols of Salalah city and play a role in both the tourist industry and urban landscaping. In early 2009, twenty-nine sites, representing Oman coconuts on beaches and cultivated lands were chosen from the Dhofar region. COGENT descriptors and DNA analysis were used for the purpose of identifying coconut germplasm available in Oman. The presence was confirmed of varieties that were imported during the 1980s, such as Yellow Dwarf, Green Dwarf and King coconut from Sri Lanka, as well as Malayan Yellow Dwarf and F1 hybrids. The local Oman Tall has the same phenotypic characteristics as other coconuts of South Asia, East and West Africa, the Caribbean and the Atlantic coast of South America. Microsatellite markers, however, reveal a substantial genetic contribution of the South-East Asian coconuts, at levels that are comparable to those found in the Comoros and Madagascar coconuts. Hypotheses about the ancestry of the Oman Tall coconuts are discussed; two genepools are indicated, consecutively involving natural selection, dissemination by floating, domestic selection and dispersal by boat.
Detection of Weligama Coconut Leaf Wilt Disease Phytoplasma by Real-Time Polymerase Chain Reaction Wijesekara, H.T.R.; Perera, S.A.C.N.; Bandupriya, D.; Meegahakumbura, M.K.; Perera, Lalith
International Coconut Community Journal Vol 36 (2020): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v36i.425

Abstract

Weligama Coconut Leaf Wilt Disease (WCLWD) is a non-lethal, but debilitating phytoplasma disease found in coconut palms in Sri Lanka which is confined to the Southern Province of the country, well-away from the major coconut growing area. If it spreads to the major coconut growing area, it might severely damage the coconut industry in Sri Lanka. Government commenced a disease control program to eradicate the disease and, more importantly to prevent spreading of the disease to major coconut growing areas. The major constraint in this program is the lack of an accurate and reliable method for identifying affected palms. Visual symptoms are used to identify the affected palms for removal, yet growers are not always convinced of the method of resisting palm removal. This poses a serious threat to the implementation of the disease control program. Although a Nested-PCR-based disease diagnosis was established earlier, the detection rate and reliability need further improvements. Therefore, an urgent necessity for a more reliable disease detection method has arisen. In the current study, a Real-Time Polymerase Chain Reaction (qPCR) powered by a pair of primers and a probe designed from the published partial sequences of the WCLWD phytoplasma was validated with 202 coconut samples and a detection rate of above 95% was achieved. This newly established detection system was highly reliable and a way forward for controlling the WCLWD disease in Sri Lanka.
Co-Authors Al-Shanfari, Abdulaziz Bandupriya, D. Baudouin, Luc Bourdeix, Roland Dissanayake, H. D. M. A. C. Fadhil, Anwar Bait Fernando, S. C. Herath, Chaminda Hountondji, Fabien C. C. Legrand, Baptiste Meegahakumbura, M. G. M. K. Meegahakumbura, M.K. Perera, S. A. C. N. Perera, S.A.C.N. Perraut, Angélique Santha, E. S. Sarathchandra, S. R. Wickramananda, I. R. Wijekoon, Rusitha Wijesekara, H.T.R.