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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

Mining resistance alleles of gene Xa38 for bacterial blight resistance in Sri Lankan rice accessions
(University of Peradeniya, Sri Lanka, 2021-11-11) Edirisingha, I.K.; Perera, S.A.C.N.; Jayatilake, D.V.
Bacterial Blight (BB) caused by Xanthomonas oryzae pv. oryzae is one of the devastating rice diseases in Sri Lanka. Currently, 42 genes have been identified as important for conveying BB resistance, out of which Xa38 (Os04g53030) is considered as a gene with major importance. For marker-assisted selection of Xa38 resistance allele, a co-dominant linked-marker (Os04g53050-1) designed based on an adjacent gene (Os04g53050), co-segregating with Os04g53030 is recommended. Among Sri Lankan germplasm, the Xa38 resistance allele carrying rice accessions have not been identified to-date. In the current study, a panel of 48 rice accessions was genotyped using the marker Os04g53050-1 and 12 traditional Sri Lankan rice accessions (Batapola el, Dik wee, Halsuduwee, Herath banda, Sudu goda wee, Kuru wee, Suwadel, Katteyaran, Mada el, Pachchaperumal, Gonabaru and Mahakuru wee) and 21 newly improved Sri Lankan varieties were identified as resistance allele carriers for Xa38. These accessions can be used as Xa38-mediated resistance donors in future rice breeding programs. Further, the present study focused on the development of an intragenic marker for the Xa38 gene as an alternative to the currently used linked-marker. Haplotypes were defined to identify a potential site for designing an intragenic molecular marker. Haplotyping was carried out using the coding sequence of Os04g53030 from 2,395 rice accessions sequenced in the 3K Rice Genomes Project. Based on the multiple sequence alignment, haplotype- defining polymorphisms with ≥5% occurrence in the panel of accessions (64 single nucleotide polymorphisms and 13 insertion/deletion sites) were identified and was used to define 20 confirmed haplotypes (H1 to H20; ≥1% occurrence frequency in the panel of accessions). Further investigation is underway to develop an intragenic molecular marker based on the identified polymorphic target sites.
Comparison of physicochemical properties of twelve iced teas in Sri Lanka
(University of Peradeniya, Sri Lanka, 2021-11-11) Wettimuny, D.; Wickramasinghe, I.
Tea is the second most consumed beverage in the world and there are many variations of tea that are manufactured around the world. Iced tea is one such beverage and the industry has grown tremendously over the past few years. But the data available on the quality of the Sri Lankan iced tea products are scarce. Therefore, the aim of this study was to analyse the physicochemical properties of different iced teas available in the Sri Lankan market in order to assess their quality. Twelve different iced teas were tested;they were aqueous extracts of green (G) and black tea (B) iced concentrates, three peach flavoured teas (P₁, P₂, P₃), two strawberry flavoured teas (S₁, S₂), ginger (G₂), lemon (L)and apple (A) flavoured tea, unflavoured iced tea of black tea (B₁) and green tea (G₁).The physicochemical parameters polyphenol content (TPC), antioxidant activity (AA), titratable acidity (TA), total soluble solids (TSS) and turbidity were measured using standard protocols. The free radical scavenging ability was analysed using the DPPH assay and TPC was examined employing the Folin-Ciolcalteu method. TA was determined as per AOAC methods, and TSS was measured using ATAGO Hand Held Refractometer MASTER-53T. The turbidity was assessed by using Thermo Scientific Eutech TN-100 Waterproof Turbidimeter. The highest level of AA was recorded in G₂ and the lowest in B₁ as 32.5 μg/ml and 3.65 μg/ml, respectively. Whereas the greatest amount of TPC was noted in G₂ at 20.08 μg/ml and the least was found in B₁ at 1.45μg/ml. The highest level of TA was found in B₁ at 2.56 g/l and lowest level of TA was noted in both P₁ and L at 1.28 g/l. The highest was reported in B₁ at 13.2 °Bx and lowest level of TSS was showed in G₂ at 6.4 °Bx. At 3.35 NTU, the least amount of turbidity was documented in L and the greatest in B₁ at 57.9 NTU. Out of the twelve types, ginger flavoured tea showed the best quality whereas the unflavoured iced tea of black tea demonstrated the poorest quality.
Effect of scheduled irrigation and fertilizer application on growth and fruit quality of mandarin (citrus reticulate balanco) variety ehime
(University of Peradeniya, Sri Lanka, 2021-11-11) Namamuni, U.D.D.; Somachadra, K.P.; Dissanayake, P.K.
Mandarin (Citrus reticulate. Blanco) production in Sri Lanka is very low while the fruit quality is highly variable. As a solution, the Department of Agriculture introduced an improved mandarin variety "Ehime", which is highly responsive to water and nutrients and having a high production capacity. The objective of this study was to evaluate efficiency of different fertilizer mixtures under proper moisture conditions of soil on plant growth and fruit quality of Ehime mandarin variety under Sri Lankan field conditions.Two Irrigation levels; Rain-fed as control (Ir₁), Scheduled irrigation (50 L water in five days interval) (Ir₂), were tested with four fertilizer treatments; Department of agriculture (DOA) recommendation (F₁), DOA+Micro nutrients (F₂), DOA+Organic manure (F₃), DOA+Micro nutrients+Organic manure (F₄),in a Split Plot design using 4 replicates. Leaf chlorophyll content (SPAD readings), width and height of plant canopy,fruit quality (fruit length, breath, hardness, peel to flesh ratio, brix value, juice content and acidity) were measured. Drastic reduction of leaf yellowing was found in F₄ and F₂ in both irrigation levels after two weeks of treatment, and yellowing was completely disappeared after two months with increasing leaf chlorophyll content. Significant increments of plant height and canopy width were observed, irrespective of the irrigation level in F₄. Heavier fruits were found in F₄ and F₂ irrespective of the irrigation. Hardest fruits were found in F₄with Ir₂. Except F₁, all other treatments showed an equal juice content irrespective of irrigation. High brix values were recorded in F₂ and F₄ with Ir₂.Peel to flesh ratio was highest in F₂ and F₄ with Ir₂. Proper plant growth and heavier fruits could be achieved when DOA fertilizer recommendation was amended with micro nutrients while supplementary irrigation with micro nutrients and organic manure amendment further improved the fruit quality.
Phenotypic evaluation of a core rice panel for sheath blight resistance
(University of Peradeniya, Sri Lanka, 2021-11-11) Thamali, K.I.S.; Nanayakkara, N.H.L.D.L.D.; Suriyagoda, L.D.B; Weerasinghe, W.D.P.; Jayatilake, D.V.
Sheath blight (SB) caused by Rhizoctonia solani Kühn is a major rice (Oryza sativa L.)disease, second only to rice blast. Host plant resistance is the most economical and environmentally-friendly approach for SB disease mitigation. However, there is limited knowledge on resistance donors for the use in rice breeding programs. Hence, the current study is the first to report the screening of 60 rice accessions including traditional and newly improved Sri Lankan rice germplasm and exotic lines for SB resistance. The study was conducted in a replicated field trial, during the yala season of 2019. At early booting stage, rice plants were artificially inoculated by placing cultured R. solani mycelia at leaf bases and three weeks after inoculation, disease progression was scored following the IRRI standard evaluation system (SES; 0 to 9 scale) derived based on percentage vertical spread of the lesion (VSL) along the plant. The Friedman test carried out using SES scores revealed three significantly different groups (p≤0.05). Rice accessions Kaluheenati, Bw267-3 and Kalundai samba were identified as resistant to SB (SES scale 0 to 1) and were reported as similar to each other (p>0.05). Of these, Kaluheenati could be identified as a resistant accession reporting a median SES (mSES) score of 0,indicating no VSL upon inoculation. Further, 23 rice accessions were identified as susceptible to SB (SES scale 7 to 9) and were similar to each other (p>0.05). Of these,the ten accessions (Gonabaru, Pachchaperumal, Dikwee, Halsuduwee, Moraberakan,Wannidahanala, Yakadawee, Bg250, Bg251 and Ld99-12-38) reported a mSES score of9 with a VLS of 65-100%. The remaining 34 accessions expressed intermediate SB disease responses (SES scale 3 to 5) and were similar to each other (p>0.05). Were commend the use of Kaluheenati, Bw267-3 and Kalundai samba as SB resistance donors for QTL mapping and future rice breeding programs.
Impact of different controlled, released and stabilized urea-based N fertilizers on productivity and nitrogen use efficiency of maize (Zea mays L)
(University of Peradeniya, Sri Lanka, 2021-11-11) Senevirathne, S.M.P.; Gunawardena, M.; Nissanka, S.P.
Nitrogen use efficiency (NUE) of irrigated maize ranges from 25-50% due to the heavy losses of applied nitrogen (N). These losses raise significant threats to the environment as well as to the human health. Hence, mitigation of these losses and enhancing the NUE of maize is vitally important. Use of controlled released fertilizers (CRF) and urea stabilizers are commonly adopted methods to enhance the NUE. A field experiment was conducted at the Dodangolla Field Experimental Station (soil type – Reddish Brown Earth [RBE]), Sri Lanka to evaluate the performance of 2 CRFs types with respect to the agronomic efficiency of N (AEₙ) in irrigated maize (variety – Pacific 984). A total of 10 fertilizer treatment combinations were used in the study. They were, two CRFs (single polymer coated and double polymer coated), used with and without DCD (Dicyandiamide) and NBPT ([N-(n-butyl) thiophosphorictriamide]), under 2 rates of urea(100% [325 kg/ha] and 50% [162.5 kg/ha] of Department of Agriculture [DOA] recommendation, and a no nitrogen applied control. DCD and NBPT rates were 10% and 1% of urea nitrogen amount (weight basis), respectively. Experimental design was randomized complete block design (RCBD) with three replicates per treatment. Plant height, leaf area, leaf chlorophyll level and yield components were measured. Results showed a 31.5% increase in AEₙ of coated, 50% N + stabilizer treatments compared to 100% N treatments. Yields of the 50% N treatments were 20.3% lower compared to 100% N treatments (P≤0.05). There was no significant difference among the 2 CRF types regarding the yield and AEN. In conclusion, compared to un coated urea, the use of CRFs in combination with urea stabilizers could improve the NUE of maize. The findings show a promising way of reducing urea application for Sri Lankan maize cultivations resulted by less N losses.