Junior Research Symposia
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Item Evaluating the most appropriate control method of Mimosa pigra; case of Mahaweli River Basin(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Geekiyanage, G.K.; Geethanjalee, P.H.K.; Gunadasa, D.M.N.H.; Inshaf, I.M.; Bandara, W.A.R.T.W.Mimosa pigra can be identified as on the worst invasive species and it can be found in certain parts on wet and intermediate zones of Sri Lanka. It can be grown at any elevation and found in low, up and mid country of Sri Lanka. It is clerly visible a 30 to 35 km belt of Mimosa pigra along the upper catchment areas of Mahaweli River. People in the area complain that this species has become a problem for them in their regular farming activities. This study was carried out in identifying community attitude towards Mimosa pigra and its control methods. A community survey was carried out covering three GN divisions in the area; Nathtarampotha, Pilapitiya, and Pandiwatta by selecting 90 families. According the results obtained there were very few uses of “Yoda Nidikumba” and surrounding people are using the plant mainly as a fuel wood. Uprooting plants before getting matured, cutting,slashing and tilling are identified by the community as mechanical control methods. However, community is unable to suggest a proper control method for preventing spread of M.pigra. According to respondents, still no proper attempt has been made by responsible parties. However, Mahaweli Authority is attempting to control the species by introducing large trees which provide shades such as Acacia acuminate (Jam) and Terminalia arjuna (Kumbuk). By studying the seed germination of Mimosa pigra under light and shade conditions it is proven that the light condition is most preferable for the success growth of the Mimosa pigra. Maintaining a shady condition in the invaded area inhibit the seed germination and growth of M.pigra. Study revealed that Gliricidia sepium (Watahiriya) can be introduced for the land as a pioneer species to control the Mimosa pigra while fertilizing the soil. Seed Germination Indexes were found for Zea mays, Vigna unguiculata along with Mimosa pigra by supplying same conditions using soil samples from the study site. Zea mays is the most suitable variety for the study site which can be grown where Mimosa pigra is dominant. Vegetation cover and water management system are best management activities for reducing the germination of Mimosa pigra seeds. It is important to carry out more studies about Mimosa pigra in this area as the flood plains of the Mahaweli River is being invaded by this particular invasive species day by day. Monitoring must be continued at the study site longer than the known seed longevity to ensure that the seed bank is exhausted, and that no further germination occurs.Item Evaluating suitable environmental conditions for seed germination of invasive Mimosa pigra; case of Mahaweli River Basin(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Geekiyanage, G.K.; Geethanjalee, P.H.K.; Gunadasa, D.M.N.H.; Inshaf, I.M.; Bandara, W.A.R.T.W.Mimosa pigra is listed as one of the 100 “World’s Worst” invasive species and it has been accidentally introduced to Sri Lanka. At present, it has been naturalised in certain parts of the country and causes a massive threat to particular ecosystems. Mimosa pigra is spreading along the upper catchment areas of Mahaweli River forming dense thickets belt along 30 to 35 km along the Mahaweli River basin where the water is used specially for irrigation activities. Mimosa pigra seeds are dispersed with the sand for construction which extracted from the Mahaweli River and its tributaries. Also, the seed dispersal with the flow of water is high especially in the rainy season. Therefore, it has become a major threat in Victoria catchment area in Kundasale with the Mahaweli development water project. In Sri Lanka it was found that seeds remained 100% viable at the room temperature (280C). There is no proper literature which says about its reproductive capacity. Still no proper attempt have been made to address this issue by responsible parties. Pre analysis of Mimosa pigra was carried out at the in front of the Central Environmental Authority. The case study was carried out at a selected study site at Kundasale (GN division –Pandiwatta) where Mimosa pigra is dominant. A preliminary survey was done in Kundasale site in order to get an idea about the study site. Three areas have been identified; clay soil area, sandy clay soil area and sandy soil area, to lay out plots in the study site. Three 20*20m plots were laid one at each site and stocking density of the study site was estimated. Seed Germination Index was calculated from prepared composite soil sample of five random locations of each plot and separately for sandy, silt and clay soil samples. Physical and Chemical properties of soil in three different sites were analyzed. Mimosa pigra has shown certain attributes as weeds and it is able to tolerate all type of soils and Sandy loam soil is the most preferred soil type under the low amount of organic matter. Study revealed that the Neutral soil pH and normal environmental temperature (27-280C) is most suitable for the growth of the M.pigra. Seed Germination Index of Mimosa pigra was found to be 80% in a shady condition and 100% with full sunlight.