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Control of spatial effects due to neighboring palms in coconut (Cocos nucifera) experiments T. S. G. Peiris
International Coconut Community Journal Vol 23 No 2 (2007): CORD
Publisher : International Coconut Community

The RCBD is the most robust design for field experimentations in coconut. In this study the effect of neighboring palms to control local variation in field experiments of coconut was evaluated using two long-term coconut trials. Four types of spatial models are suggested to consider the spatial effect due to neighboring palms and the use of such models is illustrated using two long-term field experiments. When data were analyzed separately by years or using repeated measures analysis, significant percentage reduction of CV was observed in all four spatial models relative to the RCBD model without covariates as well as pre-treat data as covariate irrespective of the experiment. Inclusion of the mean of two neighbouring palms in N-S or E-W direction as a covariate was clearly superior to the RCBD without covariate as well as pre-data as covariate when data were analyzed separately by years. Inclusion of the mean of four neighbouring palms in N-S and E-W direction as a covariate was superior to repeated measures analysis in reducing local variation, irrespective of experiments. It is recommended to include effect due to neighbouring palms when analyzing field experiments in coconut. The methodology can be applied to other tree crop experiments as well.

Factors influencing the use of coconut oil by the householders in Sri Lanka and their policy relevance to popularize the consumption of coconut oil T. S. G. Peiris; M. T. N. Fernando; S. Samarajeewa
International Coconut Community Journal Vol 20 No 2 (2004): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v20i02.388

In recent past the concept on the use of coconut oil (CNO) by the householders in Sri Lanka has been changing due to various reasons. The reasons were studied using the generalized linear models for the survey conducted during May/June 2001 for 366 householders representing three different population sectors (urban, rural and estate) and different income groups. The significant factors influencing the use of CNO are the type of oil used in past, monthly income, quality of CNO, misconception about CNO and the population sectors. The percentage of non-CNO users is considerably higher in the urban sector, whereas CNO still is the major edible oil in the rural and estate population sectors of Sri Lanka. The percentage of householders using CNO in the sample was 91.2. In 75% of the sample, the quantity of CNO consumption per person has reduced over the last five years. The main reason for dissatisfaction for CNO is adulteration. The proportion of CNO use was significantly higher in lower income groups than the higher income groups. The proportion of the CNO use decreased sharply when the income increases above Rs. 40,000 per month. The high-income earners have shifted their preferences towards other edible oil consumption. The findings of this study suggest that the growth of the per capita incomes and the rapid urbanization in the country further reduces the consumer demand for coconut oil, unless there are effective marketing strategies implemented to promote the CNO consumption in the long run. Both the proportion and rate of CNO use can be increased through an effective campaign via media. Improving the quality and dispelling the misconception among the householders would give better prospects to the coconut oil industry in Sri Lanka.

FORECASTING THE CROP YIELD OF A COCONUT ESTATE T. S. G. Peiris
International Coconut Community Journal Vol 5 No 02 (1989): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v5i02.226

Seasonal Autoregressive Integrated Moving Average (ARIMA) process of (0,1,2) x (0,1,1) x 6 that best fits a set of crop‑wise coconut yield data, in Bandirippuwa, Lunuwila is identified without using variance stabilization transformation. In this process the present value of the series may be described as a linear function of the past observation of the series and past disturbances. The physical factors such as rainfall, temperature, day length etc. are not required for this method, however the past crop figures in the estate is needed. While such model is useful for short term forecasting, it also gives the upper and lower limits of the forecasts at a given probability. These intervals would provide the quantified information on the degree of duration of the forecasts.

Control of spatial effects due to neighboring palms in coconut (Cocos nucifera) experiments T. S. G. Peiris; P. Waidayaratne; S. Samita; O. Thattil
International Coconut Community Journal Vol 23 No 2 (2007): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v23i2.166

The RCBD is the most robust design for field experimentations in coconut. In this study the effect of neighboring palms to control local variation in field experiments of coconut was evaluated using two long-term coconut trials. Four types of spatial models are suggested to consider the spatial effect due to neighboring palms and the use of such models is illustrated using two long-term field experiments. When data were analyzed separately by years or using repeated measures analysis, significant percentage reduction of CV was observed in all four spatial models relative to the RCBD model without covariates as well as pre-treat data as covariate irrespective of the experiment. Inclusion of the mean of two neighbouring palms in N-S or E-W direction as a covariate was clearly superior to the RCBD without covariate as well as pre-data as covariate when data were analyzed separately by years. Inclusion of the mean of four neighbouring palms in N-S and E-W direction as a covariate was superior to repeated measures analysis in reducing local variation, irrespective of experiments. It is recommended to include effect due to neighbouring palms when analyzing field experiments in coconut. The methodology can be applied to other tree crop experiments as well.

Fortification of coconut oil with sesame oil through micro expeller extraction process J. M. N. Marikkar; J. M. M. A. Jayasundara; W. S. R. Fernando; T. S. G. Peiris
International Coconut Community Journal Vol 22 No 2 (2006): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v22i2.171

Value addition to coconut oil is highly desirable in order to increase the range of coconut products. A study was conducted to formulate palatable coconut oil (CNO) blends enriched with essential fatty acid (EFA) using sesame seed as the supplementary source of EFA. For this purpose, micro-expelling process was employed to extract oil blends out of the dried coconut grating mixed with varying proportion of sesame seed (w/w; 0, 1, 2, 3, 4, 5, 7 and 10%). A sensory evaluation by a 30-member semi-trained panel was conducted using a seven-point hedonic scale in order to determine the critical limit of CNO fortification with sesame. Similarly, changes in fatty acid composition were determined using Gas Liquid Chromatography (GLC). Statistical analysis of the sensory data showed that a mild odor of sesame started to appear in the oil blends at 4% level of sesame mixed with dried coconut gratings. According to fatty acid methyl ester (FAME) analysis, the relative increase in linoleic acid was only marginal although there was a substantial increase in unsaturated fatty acid component. At 5% level of fortification, the increment in linoleic acid was 9.2%.

Factors influencing the use of coconut oil by the householders in Sri Lanka and their policy relevance to popularize the consumption of coconut oil T. S. G. Peiris; M. T. N. Fernando; S. Samarajeewa
International Coconut Community Journal Vol 20 No 2 (2004): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v20i02.388

In recent past the concept on the use of coconut oil (CNO) by the householders in Sri Lanka has been changing due to various reasons. The reasons were studied using the generalized linear models for the survey conducted during May/June 2001 for 366 householders representing three different population sectors (urban, rural and estate) and different income groups. The significant factors influencing the use of CNO are the type of oil used in past, monthly income, quality of CNO, misconception about CNO and the population sectors. The percentage of non-CNO users is considerably higher in the urban sector, whereas CNO still is the major edible oil in the rural and estate population sectors of Sri Lanka. The percentage of householders using CNO in the sample was 91.2. In 75% of the sample, the quantity of CNO consumption per person has reduced over the last five years. The main reason for dissatisfaction for CNO is adulteration. The proportion of CNO use was significantly higher in lower income groups than the higher income groups. The proportion of the CNO use decreased sharply when the income increases above Rs. 40,000 per month. The high-income earners have shifted their preferences towards other edible oil consumption. The findings of this study suggest that the growth of the per capita incomes and the rapid urbanization in the country further reduces the consumer demand for coconut oil, unless there are effective marketing strategies implemented to promote the CNO consumption in the long run. Both the proportion and rate of CNO use can be increased through an effective campaign via media. Improving the quality and dispelling the misconception among the householders would give better prospects to the coconut oil industry in Sri Lanka.

Impact of Covariate on Single Palm Plot Experiments in Coconut J. D. J. S. Kularatne; T. S. G. Peiris; S. Samita
International Coconut Community Journal Vol 24 No 2 (2008): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v24i2.549

The most robust design in field experiments of coconut is the randomized complete block design (RCBD) with plot size of six palms. It has now become a serious problem in finding homogenous blocks for experiments in coconut and therefore a single palm plot has been recommended by the authors. This study found that single palm plot with covariate as pre yield data is the most suitable method to reduce the unknown variability of coconut palms based on analysis of data of seven concluded field experiments on cultural management and fertilization of coconut with plot size of six palms. The percentage reduction of CV in single palm plot with covariate with respect to single palm plot without covariate varied from 21% to 60% irrespectively location, period and type of the experiment. The percentage reduction of CV in single palm plot with covariate with respect to six palm plots without covariate was 40% to 71%. Thus single palm plot is recommended for field experiments in coconut except under special circumstance such as for coconut based farming system trails (CBFS).The methodology developed to select single palm from the concluded experiments with plot size more than one can easily be applied for similar studies in other tree crops.

Impact of the coconut mite (Aceria guerreronis Keifer) on the coconut industry in Sri Lanka I. R. Wickramananda; T. S. G. Peiris; M. T. Neil Fernando; L. C. P. Fernando; S. Edgington
International Coconut Community Journal Vol 23 No 1 (2007): CORD
Publisher : International Coconut Community

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37833/cord.v23i1.559

The coconut mite (Aceria guerreronis Keifer) was first reported in Sri Lanka in 1997. Since then it has been a serious threat to the coconut industry. Feeding of coconut mites beneath the perianth of developing nuts result in scarring of the nut surface. In severe infestations, reduced nut size and nut malformation can also occur. A survey was carried out during 2003/2004 in five mite infested zones (MIZ) of Sri Lanka to assess the impact of coconut mite on various sectors of the coconut industry. The percentage of damaged nuts due to coconut mite was significantly different between the MIZ. There were also variations relative to nut size and shape. Irrespective of spatial and temporal variability, nut loss per mite infested palm was estimated to be 15.9% per annum. A 2-3% slowing down in the growth of annual national coconut production was projected due to coconut mite infestation. The loss to the coconut grower, selling at the rate of SLR 15/nut, was estimated to be Sri Lankan Rupee (SLR) 6240/ha (57.25 US$/ha) if the estate was mite infested. The de-husked weight and fresh husk weight of a coconut nut were also significantly different in relation to the mite damage and nut size and shape. From a randomly selected 10,000 nuts, the reduction of fresh husk weight was approximately 15% as a result of mite infestation, together with a loss of around 195 kg of desiccated coconut. All of the impact indicators varied significantly both spatially and temporally.

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