Browsing by Author "Nadungamuwa, D. M. H. S. K."

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Bioremediation potential of wood-associated fungi in Rajawaka forest reserve, Balangoda
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Nadungamuwa, D. M. H. S. K.; Kannangara, B. T. S. D. P.; Daranagama, D. A.
Sri Lanka consists of a high diversity of fungal species, especially wood-associated fungi. These fungi play a vital ecological role in wood decomposition and have potential applications in environmental remediation due to their unique enzyme systems. Currently, the accumulation of polycyclic aromatic hydrocarbons (PAHs), mainly from vehicular emissions has become a significant environmental concern. Therefore, the present study aimed to identify the woodassociated macro and micro fungi in the Rajawaka forest reserve which is a lowland secondary forest located in the Balangoda area in the Rathnapura district, and to assess their ability to degrade specific PAHs, including phenanthrene, naphthalene, pyrene, and anthracene. Identification keys followed by morphological characteristics and image-based methods were used to identify the macrofungi. Microfungi were isolated following surface sterilization and culturing on potato dextrose agar (PDA) plates. Most frequently isolated fungal strains were subjected to plate assay to assess the fungal growth in PAHs by using 8 replicates. Control plates were prepared without inoculating fungi for each PAH-incorporated media. Spectrophotometric analysis was done to determine their PAH degradation abilities using 3 replicates. Controls were prepared without inoculating fungi. Obtained data were analyzed using ANOVA and Tukey’s pairwise comparison by using Minitab 17 statistical software. The macrofungi collected from the Rajawaka forest reserve were mainly in the phylum Basidiomycota; Ganoderma sp., Pycnoporus sp., Phellinus sp., Hexagonia sp., Trametes sp., Earliella sp., Schizophyllum sp., Lentinus sp., Calocera sp., Stereum sp., Microporus sp., and Pleurotus sp. Frequently isolated microfungi included Trichoderma sp. 1, Trichoderma sp. 5, Trichoderma sp. 6, Grey sterile sp., Mortierella sp. 2, Brown sporulating sp., Humicola sp., and Aspergillus sp. 1. Mortierella sp. 2 and Grey sterile sp. were significantly effective in degrading phenanthrene (42.51%, and 34.16% respectively) and naphthalene (41.27%, and 33.48% respectively), while Humicola sp. and Grey sterile sp. showed a high degradation capacity for anthracene (33.73%, and 23.72% respectively) and pyrene (30.62%, and 19.32% respectively). All the PAHs studied were efficiently degraded by Grey sterile sp. This investigation serves as a preliminary exploration of the wood-associated macro and microfungal diversity in the Rajawaka forest reserve, and their potential in remediating PAH pollutants. It also opens the avenue for future research in finding environmental solutions for bioremediation of PAH deposition in Sri Lanka.
Influence of mucilage of Aloe vera (L.) Burm.f, Hibiscus rosa-sinensis (L.), Abelmoschus esculentus (L.) Moench and Neolitsea cassia (L.) Kosterm on seed germination and seedling growth of Vigna radiata (L.)
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Ranathunga, R. M. T. K.; Nadungamuwa, D. M. H. S. K.; Ratnayake, R. M. C. S.
Crop seed germination is one of the fundamental determinants of agricultural productivity and a process influenced by various biotic and abiotic factors. Understanding and optimizing seed germination immensely helps to enhance crop yields and ensure food security via better crop establishment and growth. This study aimed to identify the most effective botanical mucilage extract for enhancing the germination and seedling growth of Vigna radiata among various leaf and pod extracts. Pure leaf mucilage of Aloe vera (T1), Hibiscus rosa-sinensis. (T2), Neolitsea cassia (T3), and mature pod mucilage of Abelmoschus esculentus (T4) were used as the treatments along with uncoated V. radiata seeds as the control (T0). Leaves of T1 – T3 and mature pods of T4 were collected, washed, ground, and the paste was squeezed to obtain pure mucilage extracts. Surfaced sterilized V. radiata seeds were immersed in the T1 – T4 for ten minutes and placed in sterilized petri dishes layered with moistened filter paper. They were incubated at 27 oC under a relative humidity of 83 %. The number of germinated seeds was counted daily and the mean germination rate (MGR), germination time (MGT), germination index (MGI), germination energy (MGE), and coefficient of velocity of germination (MCVG) of V. radiata were calculated. The root and hypocotyl lengths of seedlings were measured during the final data collection. Six replicates were performed for each treatment and control with 120 V. radiata seeds. Based on the number of germinated seeds, T3 was identified as the least active mucilage extraction, and the same experiment was repeated with 1:1 diluted mucilage extraction (T5) under the same conditions. Data were analyzed using one-way ANOVA (at α = 0.05) and PCA in 'R' software. T2 significantly enhanced seed germination recording the highest MGI (19.1 ± 0.88), MCVG (98.3 ± 2.89 %), and lowest MGT (0.7 ± 0.05 days) while T3 reduced both germination and seedling growth (p < 0.05). According to PCA, both A. vera and H. rosa sinensis were identified as the most effective treatments. T3 and T4 were identified as the least effective and moderately effective extracts respectively. The extract of A. vera was 24.31% more effective and the extract of H. rosa-sinensis was 42.25% more effective in promoting the rapid germination of V. radiata seeds compared to the control. The study concluded that H. rosa-sinensis and A. vera can be used to enhance V. radiata seed germination as lowcost alternatives to chemical seed germination enhancers.