Browsing by Author "Ranasinghe, C.S."

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    Assessment of Compost Quality Produced with Municipal Solid Waste and Dewatered Fecal Sludge: A Case Study
    (Uva Wellassa University of Sri Lanka, 2021) Fernando, B.H.R.; Nadheesha, M.K.F.; Nirukshan, G.S.; Aratchige, N.S.; Ranasinghe, C.S.
    Application of Municipal Solid Waste (MSW) and Dewatered Fecal Sludge (DFS) compost for agriculture is promoted in many countries as a waste management strategy. The quality of any compost type and its suitability for agricultural application is mainly determined by its physical and chemical properties and the absence of risk factors such as heavy metals and pathogens. In this study, MSW and DFS compost samples collected from the Kuliyapitiya Municipal Council of the North Western Province of Sri Lanka were subjected to quality testing using standard methods. The results were compared with the standards specified under SLS 1635: 2019 for MSW compost and with the reported information for the other locally available organic manure types. The acidic pH of DFS compost reported in this study indicates the risk of its direct use as a soil amendment while the MSW compost showed a satisfactory pH, suitable for soil application. The macro nutrient contents (Phosphorus, Potassium, and Magnesium) of both compost types were very low except for Nitrogen and Calcium. Micro nutrient levels in both compost types were satisfactory where DFS compost was rich in Iron, Zinc and Copper indicating its potential to be used as a micro nutrient source with further development. High sand percentage in MSW compost and the presence of weed seeds in DFS compost reduces the overall quality of both compost types. The organic carbon (OC) content in MSW compost was at a satisfactory level but the DFS compost had a low OC content. Pathogens were not detected in both compost types. MSW compost showed lower levels of heavy metals than the permissible standard limit defined for MSW compost. However, DFS compost showed higher level of Mercury than the permissible standard limit for MSW compost which highlights the risk of its use as an agricultural soil amendment. In contrast, with its satisfactory OC content and the pH and the absence of pathogens and viable seeds, MSW compost has the potential to be used as a soil conditioner for soil quality improvement, but not as a nutrient source, as it has a low macro nutrient content. Keywords: Dewatered Fecal Sludge Compost; Heavy metal content; Municipal Solid Waste Compost; Macro and micro nutrient contents
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    Determination of Cultivar Differences of Coconut on Heat Tolerance by In Vitro Pollen Germination
    (Uva Wellassa University of Sri Lanka, 2013) Kiriwandeniya, K.G.S.; Alwis, L.M.H.R.; Ranasinghe, C.S.
    Coconut as one of the main commercial crops in Sri Lanka, it mainly grows in intermediate zone (around 50% of total land), wet zone (around 25% of total land) and the balance in the dry zone. Heat and drought stress are the main impacts of climate change on coconut production. Therefore, development of heat and drought tolerant coconut cultivars has been recognized as a major adaptation measure to climate change. Plant reproductive organs are more vulnerable to changes in short episodes of stress prior and during early stages of flowering (Ranasinghe et al., 2010). The major cause for failures in pollination under high temperature is reduced pollen germination at temperatures as high as 35 C to 39 C during some seasons. Therefore, it is imperative to develop tools for screening coconut for high temperature tolerance with respect to pollen germination. Several recent studies have used the in-vitro pollen germination and pollen tube growth under different temperatures to screen genotypes for high temperature tolerance. This type of pollen characteristics will provide useful insight into the reproductive tolerance of coconut to anticipated climate change. In-vitro pollen germination and pollen tube growth of typica and nana varieties were studied by Ranasinghe et al., (2010) and suggested that the response of in-vitro pollen germination to temperature will be an accurate method to screen coconut varieties to high temperature tolerance,. Therefore, this study focused on identifying the effect of temperature on pollen germination and pollen tube growth of new coconut hybrids. Methodology Six healthy coconut palms of Tall X Tall (TT), Dwarf Green X Tall (DGT), Tall x San Ramon (TSR), Brown Dwarf x Tall (DBT), Tall x Brown Dwarf (TBD), Brown Dwarf x Sa n Ramon (DBSR), Dwarf Green X San Ramon (DGSR) forms were selected randomly from Raddegoda and Mawathagama sites in Kurunegala, IL1a. The experimental design was Complete Randomized Design (CRD). Male flowers were collected from six palms of each cultivar and pollen of three randomly selected flowers was dusted into microfuge tubes with germination media and allowed to germinate in incubators. Incubators were maintained at predetermined temperatures from 16 C to 39 C within 2 C intervals (3 tubes per temperature regime). Pollen grains were counted for pollen germination (3 slides from each microfuge tube) after 22 hrs of incubation under light microscope. Germination percentage (% PG) was determined. The in- vitro elongation of pollen tubes was measured after 3 hrs of incubation by using an ocular micrometer fitted to the eye-piece of the microscope under a high power (x40). There were 18 pollen tubes per temperature regime for each variety. Maximum pollen germination percentage and pollen tube length recorded after incubation, at each temperature were analyzed using linear and non linear regression models (Ranasinghe et al., 2010). The bilinear equation (Equation 1) was used to estimate cardinal temperatures (Tmin ,Topt and Tmax) of all the varieties. Where; t is actual treatment temperature, and a, b1 and b2: equation constants. Topt: the optimum temperature for pollen germination or tube growth.