http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/71 Sun, 10 May 2026 10:56:28 GMT 2026-05-10T10:56:28Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12599 Title: Etiology of the mango stem bark blackening in Sri Lanka and in vitro biocontrol assays Authors: Herath, K.; Thiruchchelvan, N.; Manike, N.; Jayaprada, T.; Kumara, A. Abstract: Mango (Mangifera indica ) is an economically significant fruit crop in Sri Lanka. Recently, a new disease, stem bark blackening, emerged on mango in the country, causing concerns among growers. This study aimed to identify the pathogen and explore effective in vitro strategies for its management. Field observations revealed characteristic black, irregularly shaped patches encircling the mango stems and branches. Morphological studies and phylogenetic analysis of the ITS region confirmed the pathogen as Aspergillus spp. In vitro assays demonstrated 92.4% fungal inhibition by Trichoderma viride. Among the tested plant extracts, Azadirachta indica showed the highest antifungal activity (72.3% colony size reduction compared to control). Commercial fungicides tested were less effective. In vitro biocontrol activity of T. viride and A. indica extract is more effective than conventional fungicides, highlighting their potential in integrated disease management of mango stem bark blackening disease. Wed, 01 Jan 2025 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12599 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12598 Title: Assessment of morphological and genomic variation in Attakkari rice for selection of blast-resistant lines Authors: Kishanthan, A.; Terensan, S.; Gajapathy, K.; Antonyrajah, P. Abstract: Traditional rice landraces remain vital for food security and cultural identity, yet their use in breeding is constrained by insufficient characterization. This study comprehensively evaluated Attakkari, a prominent local cultivar in Northern Sri Lanka, focusing on its genetic diversity, agronomic traits, and blast resistance potential. Farmer surveys (n = 119) revealed that Attakkari is highly valued for yield (2500–3150 kg/acre), favorable taste, grain quality, and strong local market demand, with 95.79 % reporting consistently high preference. Despite concerns of blast susceptibility noted by 65 % of farmers, cultivation persists due to adaptability and cultural significance. Morphological analysis of seed samples identified ten clusters based on grain traits, from which nine morphotypes were selected for further study. Image sensing using RGB and grayscale intensities differentiated subtle pericarp variations into four sub-groups. ITS sequencing confirmed high genetic similarity (98.5–100 %) among morphotypes, with some sequences showing 100 % similarity to Oryza nivara from South Korea, indicating possible contributions from wild progenitors. Screening for ten major blast resistance genes revealed considerable variation; notably, Att 44, Att 06, and Att 16 carried up to nine resistance genes (Pita/Pita-2, Piz, Pizt, Pik, Pikh, Pib, Pikp, Pi1, Pi5, Pikm). Field evaluations highlighted significant agronomic diversity, with Att 94, Att 44, and Att 116 exhibiting superior vigor, yield components, and grain weight compared to reference varieties (RY, RM, Co 10). Overall, this integrated morphological, molecular, and agronomic assessment demonstrates Attakkari's strong potential for breeding programs aimed at enhancing yield, blast resistance, and sustainable rice production in Northern Sri Lanka. Wed, 01 Jan 2025 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12598 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12597 Title: Towards a Premium Curry Leaf Product: Evaluation of Murraya koenigii Variants in Jaffna for Market and Export Readiness Authors: Sathsarani, I.; Terensan, S.; Gajapathi, K.; Priyankan, S. Abstract: Curry leaves (Murraya koenigii) are highly valued for their culinary and medicinal uses, yet the diversity of local variants remains under-explored. We investigated the morphological and genetic variation of curry leaf trees in Jaffna District, Sri Lanka, and assessed key biochemical properties to evaluate their potential for high-quality export. A survey and field sampling across 128 households (all divisional areas except Delft Island) recorded cultivation practices and plant characteristics. Notably, 83% of households used no fertilizers or agrochemicals, and only 20% reported any pest or disease issues (with occasional sightings of tortoise beetles, mites, ash weevils, and foliar diseases like white spot or leaf curl). Challenges in cultivation included seasonal leaf fall, fluctuations in leaf aroma, water scarcity, and occasional low yields due to pest or disease outbreaks or drought. We identified 22 distinct morphological variants of M. koenigii, distinguished by differences in leaf size, shape, texture, color, petiole and rachis coloration, and number of leaflets per rachis. Aroma intensity varied among variants (rated 4 to 9 on a sensory scale). ITS region sequencing revealed two genetic groups among these samples, each defined by a specific nucleotide substitution at positions 199 (C→T) and 434 (C→A) of the 531 bp sequence. Biochemical profiling showed significant variation in phytochemical and nutrient content: total phenolic content ranged from 20 to 50 mg/100 g, iron from 8 to 40 mg/100 g, and phosphorus up to 273 mg/100 g in the most nutrient-rich variant. Sodium, potassium, vitamin C levels, and antimicrobial activity also differed across variants. These findings highlight the rich diversity of Jaffna’s curry leaf germplasm and underscore its economic potential. Developing a robust export market for these high-quality curry leaf variants will require effective networking and increased awareness of their unique qualities. Wed, 01 Jan 2025 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12597 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12596 Title: Effects of heavy metal exposure on the earthworm Eisenia fetida (Savigny, 1826) and vermicomposting efficiency Authors: Kayavarnan, K.; Pakeerathan, K. Abstract: Heavy metal contamination in organic wastes presents critical environmental challenge, making sustainable methods essential. Vermicomposting utilizing the earthworm Eisenia fetida,is an environmentally sound strategy for transforming these wastes, however, the potential for bioaccumulation of toxic elements within the earthworms is a major concern that can comprise both the process efficiency and the safety of the final product. This study investigates the bioaccumulation of heavy metals in Eisenia fetida using Atomic Absorption Spectrometer (AAS) of earthworm samples. Twelve 10Kg capacity bins each containing 2 kg of cow dung slurry and 1 kg teak leaves (2:1) were used for the experiment. Four different treatments (T1, T2, T3 and T4) such as Control, Captan, Mancozeb and chlorothalonil respectively. Total of 100 earthworms were carefully weighted and released into each treatment. The treatments were arranged in Completely Randomized Design (CRD) and collected data were subjected ANOVA and DMRT mean separation using SAS 9.4 version. Weights of earthworm were recorded every 14 days for 45 days. Earthworm samples were collected from each treatment and subjected to AAS analysis to quantify the bioaccumilated heavy metals. The initial mean weight across the treatments was 2.17 ± 0.12 g. After 10 weeks, the control group (T1) showed a significant increase in biomass of 29 ± 0.08% [2.80 ± 0.08 g], whereas T2 (5 g) exhibited a decrease in biomass of 12 ± 0.10% [1.97 ± 0.11 g] at P ≤ 0.05. In contrast, T3 (10 g) and T4 (50 g) treatments showed highly significant weight loss, with average biomass reductions of 17 ± 0.09% [1.92 ± 0.10 g] and 24 ± 0.11% [1.72 ± 0.09g], respectively, compared to the initial body weight at P ≤ 0.05.The study also revealed that the earthworm guts, which were treated with Captan, had accumulation of 0.004 mg/L of Pb. Thu, 01 Jan 2026 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12596 2026-01-01T00:00:00Z