Browsing by Author "Perera, K.R.S."

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Allelopathic effects of the invasive plant Wedelia (Sphagneticola trilobata L.) aqueous extract on common beans (Phaseolus vulgaris L.)
(Horizon publishers India, 2023) Perera, K.R.S.; Ratnayake, R.M.C.S.; Epa, U.P.K.
Sphagneticola trilobata (L.) Pruski is an alien invasive weed with aggressive growth habits, environmental stress tolerance, and the ability to synthesize allelochemicals. However, in many parts of the world, this plant is still recommended for use in composting, phytoremediation, and as an ornamental ground cover in gardens. The present study investigated the allelopathic effect of S. trilobata on the seed germination, growth and yield of Phaseolus vulgaris L. To analyze the allelopathic effects of S. trilobata on P. vulgaris seed germination, hundred seeds of P. vulgaris were exposed to different concentrations of the aqueous extracts of fresh and dry S. trilobata (2.5×102, 5.0×102 and 7.5×102 g/L) in Petri dishes for five days. The impact of S. trilobata aqueous extract on the growth and yield of P. vulgaris was also studied with seedlings planted in a compost soil mixture. Results of the study suggested negative impacts of S. trilobata extracts on P. vulgaris seed germination, growth and yield. P. vulgaris seed germination was significantly lower in the treatments than in the control (p<0.05). Further, P. vulgaris plants treated with fresh plant extracts at 5.0×102 and 7.5×102 g/L concentrations had significantly lower shoot height, growth rate, leaf area, fresh shoot weight, dry shoot weight, root length, pod length and yield (p<0.05) than controls. From the results of the study, it can be concluded that S. trilobata aqueous extracts have a dose-dependent allelopathic effect on P. vulgaris seed germination, growth, and yield and among the dry and fresh plant extracts, fresh plant aqueous extracts have a more significant allelopathic impact. As S. trilobata contains water-soluble allelochemical, it should not be used in biofertilizer production, phytoremediation, or as live mulch.
Potential Use of Selected Macrophytes Based Constructed Wetlands for the Treatment of Landfill Leachate
(4th International Conference on Advances in Computing and Technology (ICACT ‒ 2019), Faculty of Computing and Technology, University of Kelaniya, Sri Lanka, 2019) Perera, K.R.S.; Yatawara, M.D.M.D.W.M.M.K.
Phytoremediation using constructed wetlands (CWs) is widely practiced for the removal of contaminants in landfill leachate. The present study was planned to assess the potential of floating macrophytes (Eichhornia crassipes and Pistia stratiotes) and emergent macrophytes (Typha angustifolia and Chrysopogon zizanioides) in improving the quality of leachate discharged from a Sequencing Batch Reactor (SBR) system located at Dompe sanitary landfill, Gampaha, Sri Lanka. The batch type CWs were arranged to identify the suitable dilution of leachate (as 0%, 25%, 50% and 75%) for the optimum plant growths. Based on the preliminary investigations, the potential of improving leachate quality by (ia) E. crassipes (T501) (ib) T. angustifolia (T502) and C. zizanioides (T503) at 50% dilutions and (ii) T. angustifolia (T04) and C. zizanioides (T05) at 0% dilution were assessed in continuous flow CWs. Water quality parameters including temperature, pH, electrical conductivity, turbidity, BOD, COD, TSS, phosphate, ammonium nitrogen, nitrate, sulphate and color were tested once in five days for 40 days period. Results were subjected to One-way ANOVA followed by Tukey’s pair wise tests in Minitab 14. Two sample t-test at 95% CI was also applied as required. With respect to controls, percentage reductions of measured parameters increased in wetlands having either floating macrophyte, E. crassipes or selected emergent macrophytes. Nevertheless, among the emergent plants, C. zizanioides [(T503) and (T05)] showed the highest performance in improving leachate quality followed by T. angustifolia [(T502) and (T04)]at both dilutions. Although E. crassipes (T501) showed higher percentage reductions of the selected parameters at 50% dilutions, this is not recommended as leachate dilutions are impractical in CWs. P. stratiotes has proven unsuccessful in the present study. Therefore, among the plant species selected, C. zizanioides that performed at 0% dilution could be recommended as the best plant for the remediation of leachate draining from SBR system.