International Research Symposium on Pure and Applied Sciences (IRSPAS)

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Author: search.filters.author.Jayasekera, L.R.Subject: search.filters.subject.Invasive plants

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    Nutrient leaching of selected invasive plant materials.
    (International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Ranasinghe, E.H.A.A.; Jayasekera, L.R.; Kannangara, S.D.P.; Ratnayake, R.M.C.S.
    Thithonia diversifolia, Sphagneticola trilobata, Mikania scandens, Lantana camara, Chromolaena odorata, Panicum maximum and Mimosa pigra are fast growing invasive plants in Sri Lanka. In this study, the nutrient release potential and the weight loss dynamics during leaching of the above weeds were investigated with a view of utilizing them as sources of organic liquid fertilizers. Fresh leaves and immature shoots of the selected plant species were collected from Gampaha area. Samples were washed twice with distilled water and oven dried at 80 oC to a constant weight. For each species, thirty-six dried- leaves and immature shoots samples of 5 g were placed into 0.18 x 0.18 m2 single layer nylon mesh bags with 2 mm mesh size and submerged separately in 1 L of distilled water in plastic containers at the room temperature with three replicates each. Mesh bags without leaves and shoots submerged in distilled water were used as the control. Three mesh bags of each plant species were randomly collected at weekly intervals for a period of three months and the weight loss of plant material after drying in an oven at 80 oC to a constant weight, electrical conductivity and pH of the leachates were determined over time. At the end of the leaching experiment, nutrient contents of the leachates were determined using the standard methods. Results revealed that mass loss was significantly higher (p< 0.05) for M. scandens (97 %) followed by T. diversifolia (95.8 %) and the lowest for P. maximum (63.7 %). The highest pH and electrical conductivity were observed in L. camara (7.86±0.06) and M. scandens (2139±4.7 μS cm-I) respectively, and the lowest in P. maximum (7.40±0.02, 877±7.6 μS cm-1). Nutrient contents of the leachates of T. diversifolia; (N 160.4±2.1 mg/L, P 8.0±0.5 mg/L, K 349.0±3.0 mg/L), M. scandens; (N 142.8±3.0 mg/L, P 11.1±1.6 mg/L, K 464.3±9.0 mg/L) and C. odorata; (N 190.0±10.0 mg/L, P 9.5±1.5 mg/L, K 338.7±2.5 mg/L) were significantly higher than those of P. maximum (N 71±3.6 mg/L, P 8.3±1.2 mg/L, K 54.0±4.6 mg/L) suggesting that they could be effectively utilized as nutrient-rich sources to formulate environmental friendly organic liquid fertilizers.
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    Evaluation of nutrient and fiber content of selected invasive plants in Sri Lanka with a potential for preparing compost
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Hewavitharana, N.; Kannangara, B.T.S.D.P.; Jayasekera, L.R.; Senanayake, S.P.
    Based on availability, the amount of above ground bio-mass and the degree of use as compost in traditional farming systems Tithonia diversifolia, Chromolaena odorata, Mikania scandens, Lantana camara, Wedelia trilobata, Mimosa pigra and Panicum maximum were selected for nutrient analysis, with an attempt to investigate their potential to be utilized in preparation of cost effective, organic potting medium for cultivation of selected vegetables and ornamental plants. According to the preliminary surveys, Anuradhapura, Madawachchiya, Kandy, Gampaha, Kalutara and Kurunegala areas were selected for sample collection. Leaves and immature stem parts of the selected plants were analyzed by two samples per one location with three replicates. The total N, P and K contents were determined by Kjeldahl, vanadomolybdate and flame photometric methods respectively. Atomic absorption spectrophotometry was used for quantitative analysis of Mg, Ca, Cu Zn, and Fe. Crude fiber content was determined gravimetrically after chemical digestion and solubilization of the materials. Results obtained were statistically analyzed using SPSS statistics-22 software. The nutrient contents of T. diversifolia; N (3.28%), P (0.37%), K (2.50%), Mg (0.83%), Ca (4.92%), Cu (10 mg/kg), Zn (517 mg/kg) Fe (296 mg/kg) and M. scandens; N (3.44%), P (0.35%), K (3.30%) Mg (1.33%), Ca (3.39%), Cu (34 mg/kg), Zn (671 mg/kg), Fe (393 mg/kg) were significantly higher than that of other selected weeds. However, they showed significantly lower crude fiber contents 4.85% and 3.50% respectively. Although the nutrient content in P. maximum was significantly low N (1.27%), P (0.24%), K (1.44%) Mg (0.5%), Ca (1.55%), Cu (9 mg/kg), (Zn 181 mg/kg), Fe (267 mg/kg) and its crude fiber content (20.42%) was significantly higher than that of others. It can be concluded, T. diversifolia and M. scandens as plant materials which have higher amounts of nutrients. P.maximum which has higher content of crude fiber also can be incorporated in preparing compost in order to improve the physical properties of the potting medium.