Browsing by Author "Kanishka, W. S."

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Alternative gelling agents to develop cost effective medium for in vitro propagation of Dendrobium cv. “Big Jumbo White”
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Kanishka, W. S.; Lakmali, G. B. T.; Umesha, M. S. P.; Priyadarshan, A. I. S.; Senanayake, S. P.
In vitro propagation is the most common method of Dendrobium propagation. Commonly, agar is used as an effective gelling agent though, it is expensive. However, the developing a cost-effective method is beneficial for small-batch productions and is recommended. The objective of the current study was to evaluate the efficacy of ‘kithul’ flour (starch extracted from the pith of Caryota urens) and xanthan gum as alternative gelling agents to develop an efficient, cost-effective medium for in vitro propagation of Dendrobium. Seeds of Dendrobium cv. “Big Jumbo White” was cultured using full-strength Murashige and Skoog (MS) medium. After 90 days of incubation, 1g of Protocorm Like Bodies (PLBs) and plantlets of Dendrobium cv. “Big Jumbo White” were transferred to twelve different MS media supplemented with BAP (Benzyl Amino Purine) (2.5 mg/L) and NAA (Naphthalene Acetic Acid) (0.5 mg/L) and solidified with either agar (1:0) or with alternative agents; kithul flour (0:1) and xanthan gum (0:1) or a series of combinations of each alternative gelling agent with agar (1:4, 2:3, 3:2 and 4:1) totalling to 12 treatments with six number of replicates per each. The weight of plantlets and PLBs, number of plantlets, number of leaves, number of roots, and length of the roots were recorded as growth parameters in fortnight intervals for a period of 90 days to assess the growth performance. After 90 days of incubation, the MS medium of agar: kithul flour (1:4) of the treatment series with kithul flour and agar: xanthan gum (2:3) of the treatment series of xanthan gum, have shown significantly high performance in the growth and development of PLBs and plantlets. Four growth parameters, number of plantlets: 44, number of leaves per plantlet: 5, number of roots per plantlet: 12 and root length: 1.5 cm, were significantly high in the agar: kithul flour (1:4) medium than in the agar: xanthan gum (2:3) medium. Moreover, compared to the conventional tissue culture media prepared using only agar, the modified medium using agar: kithul flour (1:4) has shown 73% of cost reduction. In conclusion, the use of agar and kithul flour (1:4) as an alternative gelling agent can be recommended as a cost-effective medium for the development of PLBs into plantlets of Dendrobium cv. “Big Jumbo White” on a small scale in vitro culture system.
Pervasive Microplastic Ingestion by Commercial Fish Species from a Natural Lagoon Environment
(Water, 2024) Athukorala, A.; Amarathunga, A. A. D.; De Silva, D. S. M.; Bakir, A.; McGoran, A. R.; Sivyer, D. B.; Dias, B. C. G.; Kanishka, W. S.; Reeve, C.
Microplastics have emerged as a significant global environmental concern in the recent decade. The aim of this study was to elucidate microplastic contamination of commercial fish species in a natural lagoon environment. Microplastic contamination was examined in the gastrointestinal tracts and gills of 157 commercial fish from 18 species with varying feeding habits in a vital and sensitive lagoon ecosystem, which connects to the Indian ocean. Microplastics were extracted using digestion, followed by stereomicroscopic inspection using Nile Red stain, and identified via μ-FTIR analysis. Over half of studied fishes ingested microplastics (54.14%). Filaments (50%) and blue items (43%) were the most commonly ingested. Of all the fish species, Eubleekeria splendens had the highest average concentration of microplastics in GIT (1.41 ± 2.52 items/g w.w. tissues), although no statistically significant difference in amount of ingested microplastics (items/g w.w. tissues) was observed among species. The highest concentrations of inhaled microplastics were recorded in Sillago vincenti (1.38 ± 1.30 items/g w.w. tissues). The majority of the extracted microplastics (33%) belonged in the size class 500–1500 μm with rayon, polyethylene terephthalate, and polypropylene as the primary polymers. This study found no correlation between microplastic ingestion and fish species and feeding habits, but a positive correlation with fish size was observed. These findings reveal widespread microplastic contamination in edible fish, posing potential risks to commercially important species due to increasing pollution in lagoon ecosystems.