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The Most Frequent Agronomic Practices Used by the Coconut Farmers in the “Coconut Triangle” of Sri Lanka Lalith Perera
International Coconut Community Journal Vol 34 No 2 (2018): CORD
Publisher : International Coconut Community

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.

Coconut Palms on the Edge of the Desert: Genetic Diversity of Cocos nucifera L. in Oman Lalith Perera
International Coconut Community Journal Vol 27 No 1 (2011): CORD
Publisher : International Coconut Community

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.

Hybrid Testing and Variety Identification of Coconut (Cocos nucifera L.) in Sri Lanka Using Microsatellite Markers Lalith Perera
International Coconut Community Journal Vol 26 No 1 (2010): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v26i1.136

Currently, there is no reliable method for confirmation of the identity of coconut cultivars and the legitimacy of coconut hybrids. This makes serious problems in coconut breeding and seed production as the identity of coconut cultivars/hybrids can only be approximated at the very late stages of the growth based on reproductive traits owing to long juvenile period and the perennial nature of coconut. A microsatellite (SSR) marker based approach was used to develop an identification method for coconut varieties; Sri Lanka Tall, Sri Lanka Green Dwarf and Sri Lanka Yellow Dwarf, the key parents in the breeding programmes and tall x dwarf hybrids among them, using 18 coconut specific SSR primers. The validity of using yellow colour petiole as a phenotypic marker for the identification of dwarf yellow was also investigated. Two SSR primers, namely CAC20 and CNZ6 have exhibited the potential for distinguishing coconut varieties used as parents in the breeding programme and for confirming hybridity. It was revealed that yellow colour petiole is not a reliable marker for identification of dwarf yellow variety.

Origin, Domestication, Dissemination and Genetic Diversity of Coconut: DNA information Lalith Perera
International Coconut Community Journal Vol 17 No 01 (2001): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v17i01.347

Information on origin, dissemination and levels and distribution of genetic diversity in coconuts will allow plant breeders and conservationists to select better breeding materials and formulate appropriate conservation strategies. PCR-based DNA profiling of coconut palms from Sri Lanka was initially conducted using both Amplified Fragment Length Polymorphism (AFLPs) and Microsatellites (SSRs). Thirty-nine microsatellite primers specific to coconut were developed by small insert genomic library construction. Eighteen of those primers were used to analyze the same set of Sri Lankan coconut materials. Overall, the results generated by both AFLPs and SSRs were in agreement. Most diversity was found in the tall variety (Typica) (0.92 and 0.62 for AFLPs and SSRs, respectively) rather than the intermediate (Aurantiaca) and dwarf (Nana) varieties (0.82 and 0.25 for AFLPs and SSRs, respectively). A hierarchical analysis of molecular variance (AMOVA) based on AFLP data was used to quantify and partition levels of variability between and within form components. This revealed that for the inbreeding dwarf and intermediate forms most variation was observed between rather than within forms. In contrast, the out-breeding tall forms exhibited as much variation within as between forms.

CHLOROPLAST DNA VARIATION IN COCONUT IS OPPOSITE TO ITS NUCLEAR DNA VARIATION Lalith Perera
International Coconut Community Journal Vol 18 No 02 (2002): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v18i02.359

The pattern of world distribution of two major fruit morphotypes of coconuts has led to development of theories on origin, domestication and dissemination of coconut. Results of recent nuclear DNA analyses are in agreement with these theories with several other new insights. Compared to the plant nuclear genome however, the plant organelle genomes, the chloroplast genome and the mitochondrial genome are highly conserved and are maternally inherited in most angiosperms. Therefore, most useful information have come from regions of DNA located in organelle genome for studying phylogeny in angiosperms and for deducing historical information and evolutionary history of populations such as past migration routes and colonization dynamics. This study was aimed to determine the feasibility of developing polymorphic cytoplasmic markers, particularly the chloroplast markers. Chloroplast DNA variation of coconut from all coconut growing regions in the world assessed by both restriction digestions and physical separation of PCR products obtained with universal primers, by chloroplast microsatellites and by sequencing showed no variation. This tends to suggest that coconut may have gone through a severe cytoplasmic bottleneck and only one chloroplast type may have participated in the colonization process.

Detection of Weligama Coconut Leaf Wilt Disease Phytoplasma by Real-Time Polymerase Chain Reaction H.T.R. Wijesekara; S.A.C.N. Perera; D. Bandupriya; M.K. Meegahakumbura; Lalith Perera
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

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.

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