Institutional Repository

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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Paddy husk adulterated rice bran in broiler diets: impact on growth performance, nutrient digestibility and gut health
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Samarakoon, S. M. R.; Konthasinghe, K. H. M. N. B.; Weththasinghe, P.; Karunaratne, N. D.; Jayawardan, B. C.
This study evaluated the impact of dietary inclusion of paddy husk-adulterated rice bran on growth performance, nutrient digestibility, and the occurrence of intestinal lesions in broiler chicken. Five isoenergetic and isonitrogenous diets were formulated: a corn-soy-based control diet containing unadulterated rice bran and four diets containing rice bran adulterated with paddy husk at 3% (3PH), 5% (5PH), 8% (8PH) and 10% (10PH). One hundred and twenty Cobb 500, one-day old chicks were randomly fed with one of the five experimental diets (n=4 and 6 birds per replicate). The birds were provided with ad libitum water and feed for 35 days. Growth performance, relative organ weights and lengths, ileal dry matter digestibility and occurrence of small intestine lesions of the birds were assessed. Body weight gain (1483-1710 g per bird), feed intake (3137-3210 g per bird), and feed conversion ratio (1.86-2.19 g/g), showed no significant differences among dietary groups (P>0.05). Apparent ileal dry matter digestibility was also not significantly affected by the diets (P>0.05). Carcass yield and breast muscle yield remained unaffected, though gizzard and caecum weights were higher (P<0.05) in birds fed 8PH compared to those fed control diet, suggesting enhanced digestive function. Notably, birds fed 3PH reduced duodenal lesion odds (OR = 0.020, P<0.05), indicating a protective effect on gut integrity, while higher levels (5PH, 8PH and 10PH) showed no impact on intestinal lesions (P>0.05). In conclusion, rice bran adulterated with up to 10% paddy husk can be included in broiler diets without impairing growth performance or nutrient digestibility.
Distinguishing two morphologically similar Rhinacanthus species using Chloroplast barcoding regions
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Siyama, M.; Somaratne, Y.
Rhinacanthus flavovirens (Maha Anitta) belonging to the family Acanthaceae, is an endemic species to Sri Lanka. R. flavovirens is distributed in North central, Central, Southern and Western provinces in the country. R. flavovirens and R. nasutus possess a high level of morphological similarity, creating confusions in differentiating between the two species. DNA barcoding is a widely used molecular method for herbal plant identification and authentication, especially when morphological features are not sufficient. Chloroplast barcoding regions matK, rbcL and trnHpsbA have been used for this study. DNA was extracted and quantified using a Nanodrop spectrophotometer before amplification. The amplified fragment lengths for R. nasutus were 762 bp (matK), 369 bp (rbcL), and 333 bp (trnH-psbA), while those for R. flavovirens were 769 bp (matK), 370 bp (rbcL), and 364 bp (trnH-psbA). The Sanger sequencing showed that, among these three markers trnH-psbA showed the highest nucleotide variation (68.46%) whereas matK showed the lowest (1.3%). Pairwise genetic distance analysis showed that R. nasutus and R. flavovirens have closer genetic relatedness for matK region (0.0133) and higher divergence in trnH-psbA region (1.83). The MEME suite program identified a higher frequency of insertion/deletion events in trnH-psbA compared to matK and rbcL. The result of this study showed that DNA barcoding, particularly using variable region trnH-psbA, can effectively distinguish R. flavovirens from R. nasutus. Future studies incorporating whole chloroplast genome sequencing may provide enhanced resolution for species identification, authentication and phylogenetic analysis.
Economic and environmental viability of dairy cattle farming in areas under tea plantation: a case study in Gouravilla Grama Niladhari Division, Central Province, Sri Lanka
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Manojpraba, S.; Silva, G. L. L. P.
This study evaluated the economic profitability and environmental sustainability of dairy farming in tea plantation areas, focusing on 96 household dairy farms in the Gouravilla GN Division, representing the entire dairy-farming population in the area. Data were collected through a structured questionnaire and field observations, and analyzed using SPSS with descriptive statistics, Spearman rank-order correlation, Pearson correlation coefficients, and the Kruskal-Wallis test. Economic profitability was estimated using monthly average net income based on Wood’s equation-predicted milk yields, farmgate prices, and reported feed and variable costs. Profitability was mainly affected by poor breeding management, unstable milk pricing, and limited herd expansion opportunities. Poor breeding contributed to extended lactation lengths, prolonged calving intervals, reduced milk yields, fewer calves per cow lifetime, and reduced income. Unstable farmgate milk prices controlled by intermediaries’ further diminished profitability, as 83.4% of farmers received 140 LKR or less per litre of milk. Monthly average net income positively correlated with number of milking cows (r = 0.665, p < 0.01) and herd size (r = 0.320, p < 0.01). However, herd expansion was constrained by limited quality feed, insufficient financing, and land scarcity, with 28.1% of farmers lacking land for pasture. Low awareness of greenhouse gas emissions, manure handling, and animal welfare highlighted environmental sustainability gaps. This study further emphasizes strengthening breeding programs, ensuring fair milk pricing through formal collection, improving feeding based on local resources, and enhancing sustainability awareness are necessary to support profitable and environmentally responsible household dairy farming in tea plantation regions specially in upcountry
An investigation into the floral Biology of King-coconut and developing a protocol for artificial hand pollination
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Thilakarathne, M. G. O. S.; Perera, S. A. C. N.; Dissanayaka, H. D. M. A. C.
King coconut (KC) is an intermediate-type coconut form in Sri Lanka and a popular natural beverage. Despite its importance, floral biology remains largely unresearched. The objective of the present study was to investigate the key floral phases of KC in IL1a and IL3 agro-ecological regions (AERs) of Sri Lanka and to develop a protocol for artificial hand pollination. Seven palms aged 18-20 years were randomly selected per AER. All inflorescences emerging between December 2023 and December 2024 were recorded, totaling 74 in IL1a and 66 in IL3. The duration of the key floral phases of each inflorescence were recorded. A general linear model was employed to compare the two locations. The male phase began simultaneously with spathe opening of the inflorescence and lasted approximately 11-12 days in both regions. The female phase began 5-6 days after inflorescence opening and lasted for approximately seven days in both regions. A five to six-day overlap between the male and female phases was observed, indicating a predominant self-pollination breeding behavior in KC. Notably, the extended female phase over the male phase explains the presence of natural hybrids among progenies produced through open pollination. Based on these results, a stepwise hand-pollination protocol was proposed for KC, involving emasculation, bagging, artificial pollination, and subsequent bag removal. This research enhances knowledge of the reproductive biology of KC and offers guidelines for breeding programs, conservation efforts, and the establishment of seed gardens.
Anatomical, biochemical and physiological traits associated with drought tolerance in wild rice oryza rhizomatis vaughan
(Postgraduate Institute of Agriculture (PGIA), University of Peradeniya, Sri Lanka, 2025-11-21) Adhikari, A. M. D. M.; Abhayagunasekara, A. V. C.; Bandaranayake, P. C. G.
Water scarcity remains a key limitation in rice cultivation, underscoring the need for droughtresilient rice varieties. Oryza rhizomatis, an endemic wild rice species, represents a valuable genetic resource for enhancing drought tolerance in cultivated rice. This study investigated anatomical, biochemical, and physiological traits in two contrasting O. rhizomatis accessions, namely drought-tolerant accession-1 and drought-susceptible accession-21, collected from Puttalam and Hambantota, respectively. Sixty-five days after planting, plants were subjected to progressive drought stress in a completely randomized design until completely dry. Sets of plants were maintained as a control. Leaf rolling, a key drought-responsive indicator, was assessed using the Standard Evaluation System developed by International Rice Research Institute, and total phenolic content (TPC) was measured using Folin–Ciocalteu method. Leaf and floret anatomy was studied using a light microscope. Accession-21 exhibited a higher early-stage TPC (32.22±1.77 mg GAE/g) than accession-1, likely reflecting an early oxidative defense, whereas low TPC in accession-1 indicated the tendency of conserving energy for survival by limiting phenolic synthesis. Leaf rolling differentiated drought sensitivity, with delayed rolling (11%) in accession1 versus complete rolling (100%) in accession-21 after 29 days. Anatomically, accession-1 possessed larger bulliform cells (113.00±26.70 µm height; 215.67±49.07 µm width) and thicker lower epidermis (32.37±1.60 µm; P<0.05), reducing transpirational water loss. Although anther height did not differ significantly, accession-21 showed a taller stigma (5379.2±195.6 µm) than accession-1 (4415.1±227.9 µm), suggesting a potential reproductive advantage under stress. Overall, drought tolerance in O. rhizomatis is mainly associated with structural and physiological adaptations in accession-1, while accession-21 exhibits rapid phenolic accumulation and accelerated leaf rolling. These observations underscored the potential of the species for developing drought-tolerant rice.