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U n i v e r s i t y of P e r a d e n i y a

The Institutional Repository of the University of Peradeniya is the University's digital gateway to scholarly knowledge and research excellence. Established as the next phase of the Digital Library initiative launched by the University Library in 2011, it preserves, showcases, and provides open access to the intellectual output of the University community.

Through a rich collection of research articles, conference proceedings, theses, dissertations, and other scholarly works, the repository enhances the visibility, accessibility, and long-term preservation of knowledge, extending the global reach and impact of the University of Peradeniya’s academic and research contributions.

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Recent Submissions

Riparian vegetation changes along a rural-urban gradient: a case study of the Kuru Ganga tributary of the Kalu River in Sri Lanka
(University of Peradeniya, Sri Lanka, 2023-09-20) Nayanthima, P.G.R.A.; Dissanayake, D.M.L.
A riparian zone, also known as riparian buffer, refers to the area of land situated along the banks of a river, stream, lake, or other water bodies. Considering the rural-urban gradient of the stream corridor landscape it can identify massive destruction of stream corridor ecosystem and serious damage to the riparian vegetation in stream ecosystem with increasing urbanization/anthropogenic activities. This study is focused on riparian vegetation changes along a rural-urban gradient in Kuru Ganga tributary in Kalu River, Sri Lanka. Relevant literature sources, legal documents, image classifications, belt- transect surveys, and field observations were used to conduct the study. As analysis methods: Simpson’s Diversity Index, riparian vegetation analysis, and statistical analysis were used. Simpson’s Diversity Index indicates rural segments range between 0.9-1 while urban segments range between 0-0.7. There is high vegetation species density and diversity in rural segment compared to urban segments. While the natural riparian vegetation of the study area consists of lowland wet evergreen vegetation, the riparian vegetation of average populated areas to densely populated areas mostly consists of home garden and agricultural species. Urban landscape of the study area stated a higher level of stream restoration requirements and the rural landscape of the study area still has healthy riparian vegetation conditions compared to urban. To conserve the riparian vegetation in both rural and urban landscapes government should strengthen the remaining laws and regulations and should give more power to responsible authorities to take legal actions in corridor demarcation. To achieve the sustainable status of stream corridor ecosystems there should be awareness programs for stream dwellers to maintain stream corridors and stream corridor restoration programs should be conducted to conserve native streamside flora in river basins in Sri Lanka.
Development of an extended-release insect repellent bio-composite by encapsulation of acronychia pedunculata essential oil into tonsil 134 against Sitophilus oryzae (L.) (Coleoptera: Curculionidae)
(University of Peradeniya, Sri Lanka, 2023-09-20) Chinthaka, S.D.M.; Liyanage, H.T.; Perera, A.G.W.U.
Insect pests are a persistent threat to stored grains, leading to substantial post-harvest losses. Due to the detrimental issues of synthetic pesticides, bio-pesticides have emerged as an alternative owing to their advantages in addressing those issues. Thus, the present study aimed to develop an extended-release insect-repellent bio-composite by encapsulating Acronychia pedunculata essential oil (APEO) into the adsorbent tonsil 134, against the rice weevil Sitophilus oryzae. Test insect cultures of adult Sitophilus oryzae were maintained under ambient thermo-hygrometric conditions. The APEO was extracted from leaves of Acronychia pedunculata via hydrodistillation, and the chemical composition was analyzed through gas chromatography-mass spectrometry (GC-MS). The area preference bioassay was conducted to determine the 95% repellent concentration (RC95). Subsequently, APEO content equivalent to RC95 was incorporated into the adsorbent and the prolonged repellent activity of the bio-composite was assessed through the cup bioassay. The GC- MS analysis of APEO revealed thirteen major compounds, with ocimene (33.8%) being the predominant. In the area preference bioassay, a 100% repellency was observed at the highest dose after a six-hour exposure period and the RC95 value was recorded as 3.62 μL cm-2. The cumulative release of APEO from the bio-composite was assessed using thermogravimetric analysis, which resulted in a cumulative weight loss of 52.26% by the end of 30 days. Fourier transform infrared spectroscopy confirmed the successful incorporation of APEO into the sorbent and its extended release over 30 days. Scanning electron microscopy analysis demonstrated no significant morphological changes between the pristine tonsil and the bio-composite. The cup- bioassay resulted in a percentage repellency of 100%, >90%, and 90–80% after each 10-day exposure period within a 30-day period, which correlated with the cumulative release of APEO. Thus, APEO-based bio-composite can be effectively used as an eco- friendly method to successfully control insect-pest infestations in stored-grain food systems for a prolonged period.
Evaluation of nutrients enriched biofertilizer pellets on growth and yield performance of rice (Oryza Sativa L.) under field conditions
(University of Peradeniya, Sri Lanka, 2023-09-20) Kumara, A.W.S.P.; Weerasinghe, M.P.G.S.M.; Karunarathne, K.H.M.I.; Gajanayake, B.; Manathunga, M.M.K.D.; Nuwarapaksha, T.D.
Rice (Oryza sativa L.) is the staple food for over half of the world's population. The most significant agronomic practice in paddy cultivation is fertilizer application. Excessive applications of inorganic fertilizers lead to numerous negative environmental consequences. Adapting eco-friendly techniques, like the use of nutrients enriched biofertilizers, has identified as the best possible solution to overcome the above problems. Generally, the nutrient content of biofertilizers is low compared to inorganic fertilizers. This research was conducted to produce nutrients enriched biofertilizer pellets with different amendments and to investigate their performance on the growth and yield of the Bg 251 rice variety. Fish tonic, Eppawala Rock Phosphate, Potassium Feldspar and Dolomite were used as amendments to enrich biofertilizer. The experiment was arranged in a randomised complete block design with six treatments and four replicates. Plant height, number of leaves, number of tillers, flag leaf length, number of panicles per bush, number of seeds per panicle, and seed weight were taken from five randomly selected clusters in every plot. Statistically significant difference was observed in the number of seeds per panicle over the control. The number of tillers per bush and the number of panicles per bush were significantly different, while no fertilizer treatment (T0) showed the lowest and fish tonic enriched pellets (T5) showed the highest values. The mean yield per bush was between 16.8 g (T0) and 30.3 g (T5). A significantly higher vegetative and reproductive growth performance of rice was observed with nutrients enriched biofertilizer pellets over the control. Findings of the study reveal that the nutrients enriched biofertilizer pellets have influenced the growth and yield performances of paddy. This research concludes that the biofertilizer can be used for pelletizing after enrichment of nutrients, and it has potential to enhance the performance of the Bg 251 rice variety.
Effects of phosphorus and zinc application on growth of rice (Oryza Sativa) in soils with contrasting phosphorus levels in Sri Lanka
(University of Peradeniya, Sri Lanka, 2023-09-20) Mayadunne, S.M.A.D.K.S.; Dharmakeerthi, R.S.; Attanayake, C.P.
Phosphorus (P) application can interfere with Zinc (Zn) availability for rice plant affecting their growth and yield. A pot experiment was conducted to investigate the effect of P and Zn application on growth of the rice plants in an Alfisol (S1) and Entisol (S2), with contrasting P levels. Rice (var Bg 360) were grown for 10 weeks under flooded conditions in pots (5.5 kg of soil per pot) with all possible combinations of four levels of P (0, 11, 33, and 99 kg ha-1) and three levels of Zn (0, 2 and 4 kg ha-1 ). Plant growth parameters were measured at the end of the experimental period. Mehlich-3 extractable P concentrations were 8.53 and 22.65 mg kg-1 while Zn contents were 1.99 and 1.02 mg kg-1, in S1 and S2 soils, respectively. Interaction effects of P × Zn rates were not significant on any of the plant growth parameters. Total dry matter content was significantly higher (p<0.05) in S1 than that in S2 at all P levels, but the differences of dry matter contents among the two soils were low at high P levels. The low total dry matter content in S1 could be due in part to differences in P and Zn availabilities in these soils. Irrespective of soil type and P application, total dry matter yield increased with Zn application, by 12% at 2 kg ha-1 but only by 8% at 4 kg ha-1 compared to that in 0 Zn level. These observations suggested that the application of Zn has beneficial effects in rice cultivation irrespective of the available P content in these two soils. However, to better understand the root causes for the observed effects, changes in P and Zn availabilities in these soils upon their application needs to be investigated in future studies.
Occurrence of aflatoxin M1 in cheese products commonly available in Sri Lankan market
(University of Peradeniya, Sri Lanka, 2023-09-20) Fernando, B.R.; Mudannayake, M.M.A.W.P.; Karunarathne, R.M.S.K.; Jayasooriya, P.W.; Abesooriya, K.G.A.D.; Nanayakkara, D.U.; Silva, S.S.P.
Aflatoxins (AFs) are a group of mycotoxins produced by certain fungi of Aspergillus spp. Intake of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) contaminated feed can affect the health and productivity of animals. AFM1 is a hydroxylated metabolite of AFB1 formed inside the animal body which is excreted into milk of cows consumed AFB1 contaminated feed. Consumption of AFs contaminated dairy products causes negative health effects in consumers. This study determined the occurrence and levels of AFM1 in processed cheese (n=28), hard cheese (n=14), semi- hard cheese (n=5), and soft cheese (n=3) representing seven popular brands available in the local market. The samples were analyzed by an Ultra High-Performance Liquid Chromatography Fluorescence Detector method. AFM1 was detected in 40 samples (0.11-14.43 ppb; 80.0%) out of the 50 cheese samples analyzed, and 17 (34.0%) had AFM1 levels exceeding the maximum permitted limit set by Codex Alimentarius Commission (0.5 ppb). Further, 34 samples (68.0%) had AFM1 levels above the regulatory level of the European region (0.25 ppb) and 10 samples (20.0%) violated the Sri Lankan maximum limit of 1 ppb. Thirteen out of the 14 hard cheese (0.11-14.43 ppb) and all semi-hard cheese samples (0.29-0.65 ppb) contained AFM1. Most of the soft (66.7%; 0.35-0.45 ppb) and processed (71.4%; 0.11-1.35 ppb) cheese samples had AFM1. Hard cheese products which have more milk caseins and low water content had higher AFM1 levels compared to other cheese types. Many of the locally manufactured cheese products available in the Sri Lankan market may pose health risks to consumers. Therefore, it is important to establish regulations on par with international standards and monitor the compliance of products in the market. Further, regulations to control AFs in animal feed will support the efforts to minimize AF contamination in milk and dairy products.