Browsing by Author "Sirisena, D.N."

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    Effect of Long Term Phosphorus Fertilizer Application on Phosphorus Availability and Cd Accumulation in Rice Soils (Oryza sativa L.)
    (Uva Wellassa University of Sri Lanka, 2013) Dasanayaka, I.G.C.R.; Herath, H.M.S.K.; Sirisena, D.N.
    Rice occupies approximately 33 % of the total cultivated area in Sri Lanka accounting to 0.78 million hectares (Central Bank of Sri Lanka, 2010). Plant nutrients are essential for the production of crops and in term of healthy food for the world’s increasing population. In that context, phosphorus (P) is an important nutrient in rice cultivation. P is directly absorbed form soil and makes up 0.1% - 0.4% of the dry matter in plants. It involves in carbohydrate breakdown for energy release, cell division and transfer of inherited characters. P stimulates early root growth and development, hastens maturity of plant, improves seed production and involves in energy transformation. Since supply of P from soil is not enough to obtain higher grain yields, farmers are advised to apply P fertilizer into soil. These synthetic fertilizers carry lot of heavy metals such as Cd as contaminants. Scientists are of great interest at the moment of the contamination of heavy metals to paddy fields through P fertilizer especially super phosphate (TSP). Cadmium (Cd) is a toxic heavy metal and is also known as one of the major environmental pollutants. Cd is dissolved in water, taken by crops, transferred to human body by ingestion causing health problems. This research was conducted to study the effect of P fertilizer application in the long term basis on soil fertility status and grain yield of paddy. Methodology The study was conducted at Rice Research and Development Institute Batalagoda situated in the low country intermediate zone IL1 agro ecological region of Sri Lanka (longitudes of 800 and 810 and latitude of 70 and 80 at an elevation of 65 meters above sea level). Soils of the experimental site belong to Kurunagala soil series and great soil group of Psummentichupludult. Treatments namely: no P fertilizer (T1); seasonal P fertilizer application (T2); alternative seasonal P application (T3) were used and arranged in Randomized Complete Block Design (RCBD) with four replicates. P fertilizer rates added to the above experiment were based on the recommendation given by the Department of Agriculture (Department of Agriculture, 2001). respectively. Soil samples were analyzed for available P and total P contents. Plant samples were analyzed for plant P contents. To determine Cd accumulation in soil, straw, seeds, plant and soil samples were analyzed. Having air dried and passed through 2 mm sieve, each sample was thoroughly ground into fine powder and total P, available P and Cd were measured.
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    Paddy Farmers’ Willingness-To-Pay towards Eco-Friendly Farming Technologies: Case of Adoption of Parachute Technology
    (Uva Wellassa University of Sri Lanka, 2019-02) De Silva, L.H.N.; Lakmali, C.D.A.; Jayasinghe-Mudalige, U. K.; Dharmakeerthi, R.S.; Sirisena, D.N.
    The controversial issue of an excessive usage of chemical fertilizers in paddy farming led scientists to investigate on and invent environmentally-friendly production technologies (EFTs) such as ‘Parachute Technology’ that enhances the efficiency of fertilizer uptake. What factors trigger farmers to adopt EFTs in the field, and more importantly, the “role of economics” in adoption of such technologies is, however, not yet fully disclosed. This study, in particular, explores the outcome of an economic analysis carried out to determine the Willingness-To-Pay (WTP) of farmers, as potential end-users, for Parachute Technology. Data were collected by way of face-to-face interviews supported by a structured- questionnaire from a set of farmers (n=120) registered with a multi-stage multi-criteria project on production and promotion of EFTs in Kurunegala and Anuradhapura districts. Choice experiment method was employed to elicit their Marginal WTP for individual attributes. The estimates from Conditional Logit model revealed that certain attributes, including ‘low environmental damage’ (i.e. the highest value of Rs. 7,872), ‘requirement of training’ (Rs. 5,183), ‘integration ability with other EFTs at the beginning’ (Rs. 4,099) and ‘low fertilizer wastage’ (Rs. 2,488) possess a significant relationship with farmer’s WTP. These imply that the farmers, in general, exhibits positive attitudes and willing to pay relatively high prices for eco-friendly attributes associated with EFTs like Parachute Technology, but needs to expose them to a facilitative process along with financial packages to offset short-term benefits of chemical fertilizer use.
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    Quantitative Assessment of Leaf Color Change in Response to Phosphate Deficiency Tolerance in Rice
    (Uva Wellassa University of Sri Lanka, 2013) Aluwihare, Y.C.; Lelwala, R.; Ishan, M.; Sooriyapathirana, S.D.S.S.; Sirisena, D.N.; Samarasinghe, W.L.G.
    Phosphate deficiency tolerance (PDT) is one of the important traits in improving rice varieties. Annual expenditure on phosphate fertilizers for rice is Rs.1158.4 millions in Sri Lanka. Application of phosphate fertilizers also causes many other environmental and health problems (Wickramasinghe et al., 2009). If PDT rice varieties can be developed, they can be grown with reduced fertilizer applications, higher profit margin, and minimum negative effects of phosphate applications (Wissua and Ae, 2001). Because of the phosphate deficiency, the leaf color is changed. If the color differences in leaves can be quantitatively measured, it can be used to assess the PDT of different rice varieties (Fageria et al., 1988). The present study was conducted to screen selected traditional and improved rice varieties developed by Rice Research and Development Institute (RRDI), Batalagoda (Bg) for PDT using the leaf color change measurements in a quantitative approach. Methodology A total of 10 rice genotypes (nine varieties: Bg 358, H 10, H4, Bg 360, Bg 403, Bg 379-2, Bg 352, H 7 and MAS and the landrace: Suduheenati) were grown in a field at RRDI, Bathalagoda where no fertilizer has been applied for last 30 years. Plants were maintained with standard management practices except no phosphate application. The leaf color measurements; L*, a* and b* were recorded in four replicates per plant on the sixth week after planting using a spectrophotometer (CR-10, Konika Minolta, Tokyo, Japan). L* measured the darkness/lightness range of the visual color from black (-L*) to white (+L*), a* measured the range from green (-a*) to red (+a*) while b* measured the range from blue (-b*) to yellow (+b*). The quantitative estimates, C* (chroma; estimate of dullness/sharpness of the visual color) and H* (hue angle; estimate of the overall visual color) were calculated using the following equations (Melgosa, 2000).
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    Study on response of rice varieties to different nitrogen fertilizer levels
    (Uva Wellassa University of Sri Lanka, 2015) Priyadarshanee, H.V.C.; Alwis, L. M. H. R.; Sirisena, D.N.
    Rice (Oryza sativa L.) is the single most important crop and the staple food of more than three billion people or more than half of the world’s population. Paddy is cultivated as a wetland crop in all districts. Direct or indirect involvement for paddy sector is more than 30 % of the total labour force (Wickramasinhe and Wijewardena, 2000). Rice provides 45% total calorie and 40% total protein requirement of an average Sri Lankan (Department of Agriculture,2010).The areaunder paddy production in yalaand maha was 1,671,054 Mt and 2,629,566 Mt respectively (Department of Census and Statistics, 2010). Nitrogen, phosphorous and potassium are the three major nutrients required for the rice plant. Nitrogen (N) is one of the essential macro -nutrients for rice growth and one of the main factors to be considered for developing a high-yielding rice cultivar. Nitrogen increases plant height, panicle number, leaf size, spikelet number, and number of filled spikelets, which largely determine the yield capacity of a rice plant. Panicle number is largely influenced by the number of tillers that develop during the vegetative stage. Rice plants require nitrogen during the tillering stage to ensure a sufficient number of panicles and reproductive to grain filling. Nitrogen imbalance in soil produces low fertilizer use efficiency, low yields and low farmer profit.Main nitrogen loss mechanisms are volatilization of ammonia (NH3), leaching loss of nitrate (NO3-), loss through denitrification and soil erosion (Choudhury and Kennedy, 2005).Therefore, optimum level of nitrogen fertilizer should be applied to get maximum yield of paddy cultivation and utilize nitrogen fertilizers effectively (Fageria and Baligar, 2003). Materials and Methods This study was conducted at the Rice Research Development Institute (RRDI) at Batalagoda in Kurunagala district, Sri Lanka. Fertilizers used were urea as the Nitrogen source, and others; Triple super phosphate and Murate of Potash. The experiment was comprised with sixteen treatments. Nitrogen fertilizer was applied as 0, 50, 100 and150 kg N ha-1. Four rice varieties, Bg 1350 (V1), Bg 997 (V2), Bg 379-2 (V3) and Bg 450 (V4) were tested. These four rice varieties are in age group of four to four and half months.Sixty four plots were arranged according to the split plot design with sixteen treatments and four replicates. Plant height, number of tillers per hill, plant greenness, number of days for 100 % flowering of rice varieties, dry weight of shoot parts, plant nitrogen content, number of panicles per hill and grain yield were measured against different nitrogen levels. As the results showed (Table 1) there was a significant effect (P<0.005) among the treatments for the plant height, number of tillers per hill, plant greenness, number of days for 100 % flowering of rice varieties, plant nitrogen content, number of panicles per hill and grain yield. There is no statistically significant difference among the levels of nitrogen and variety with dry weight of shoot parts.