Browsing by Author "Ratnayake, R.M.C.S."

Filter results by typing the first few letters
Now showing 1 - 20 of 22
  • Thumbnail Image
    Item
    Address on “Why plant species become invasive? – Characters related to successful biological invasion”
    (Biodiversity Secretariat, 2014) Ratnayake, R.M.C.S.
    The impact of Invasive Plant Species (IPS) on biodiversity is irreversible and enormous because plant invasions can alter the functioning of an ecosystem dramatically. They also have a negative impact on environmental, economic and public wellbeing. Invasiveness of a species is dependent on any of five key factors: regional climate, microclimate, the site, past disturbance patterns, and individual species characteristics. The main focus of this paper is on species characteristics. Invasive species show high reproductive fecundity and great capability of spreading throughout their new location. Invasive species have characteristics that allow them to thrive in the area where they are introduced. However, how the characters of invasive alien species (IAS) determine their invasiveness is one of the key questions in invasion biology and this paper describes key characters of IPS, which are of great significance for their invasiveness. Compared to the native specialists‘ plants, the IPS are generalists, capable of surviving in a wide range of climatic conditions, which produce diverse habitats and soil variations. Therefore, IAS possess a broad habitat compatibility. In their new environment, IPS are not subjected to the damages of natural herbivores and diseases to maintain their maximum population densities, and hence they monopolize habitats. IPS enhances their invasive habit successfully by efficient competition for resource utilization and creating allelopathic effects to native biota. Invasive species also have high rates of growth and reproduction with early maturity. As a result, invasive species flourish in the settled landscapes as they produce many offspring and spread in to new area rapidly (high reproductive fecundity). Phenotypic plasticity and genetic differentiation are the two major strategies of IAS, which facilitate them to adapt to new habitats and environmental heterogeneity. Characteristics that make IPA successful in our environment are discussed with appropriate examples from IPS of Sri Lanka. However, generalizations can be misleading, because studies reveal different responses of native plants to the presence of IPS. Therefore, there is a need to understand general trends and exceptions within a particular habitat.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Dichogamy: Undisclosed sexual systems of genus Bridelia in Sri Lanka
    (The Institute of Biology, Sri Lanka, 2016) Dias, M.A.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
    Effect of burying depth and surface fire on germination of selected dry zone forest plant seeds in Sri Lanka
    (Institute of Biology, Sri Lanka, 2011) Ratnayake, R.M.C.S.; Jayasekera, L.R.
  • Thumbnail Image
    Item
    Effects of foliar and soil-applied liquid organic fertilizers on the growth of Basella alba L. and Centella asiatica L.
    (The Journal of Agricultural Sciences - Sri Lanka, 2021) Ranasinghe, R.H.A.A.,; Ratnayake, R.M.C.S.; Kannangara, B.T.S.D.P.
    Purpose: Environmental-friendly organic fertilizers reduce the adverse impacts of chemical fertilizers. This study was conducted to formulate organic liquid fertilizers using selected plant materials i.e., Tithonia diversifolia, Mikania scandens, Chromolaena odorata and Gliricidia sepium with selected organic wastes to compare the efficacies of foliar and soil-applications over the growth of leafy vegetables; Basella alba and Centella asiatica. Research Method: Selected plant materials were allowed to decompose for two months and thereafter fish waste was hydrolyzed separately with fruit wastes of Carica papaya, Ananas comosus and (1:1 w/w) mixture of both were mixed and nutrients analyzed. Fertilizers were foliar and soil-applied separately on C. asiatica and B. alba in RCBD in pot trials. Findings: Fertilizer formulated with decomposed plants + fish waste hydrolyzed with C. papaya significantly recorded the highest N (0.57%), P (0.06%) and highest growth of C. asiatica and B. alba over both soil and foliar applications followed by the fertilizer formulated with decomposed plants + fish waste hydrolyzed with C. papaya + A. comosus. Foliar-application of B. alba significantly showed the highest growth than the soil-application [shoot height (36.6±3.4 cm vs 30.0±1.5 cm), number of leaves per plant (21.7±1.4 vs 17.5±0.8) and plant fresh-weight (61.5±1.8 vs 55.6±0.9 g)] whereas, C. asiatica indicated no significant difference considering both fertilizer application methods. Research limitation: Pot experiments were carried out to provide uniform soil conditions for the experiment which was the main limitation compared to field trials. Originality/value: The formulated novel fertilizers could be utilized effectively in organic farming for safe and healthy leafy vegetables which reduce the adverse impacts of chemical fertilizers.
  • No Thumbnail Available
    Item
    Effects of Low-Cost Organic Fertilizer Derived from Invasive Alien Plants and Shade on Growth Performances and Yield of Aloe vera (L.) Burm.f.
    (Institute of Biology, Sri Lanka, 2021, 2021) Bandaranayake, A.R.B.W.M.C.D.; Ratnayake, R.M.C.S.
    Aloe vera is a popular herb for cosmetic and medicinal industries at the global level. The study was conducted to evaluate the effects of organic liquid fertilizer (OLF) from invasive alien plant species (IAPS), Mimosa
  • Thumbnail Image
    Item
    Efficacy of lquid organic fertilizers on growth of Anthurium andraeanum L.
    (Institute of Biology, Sri Lanka, 2015) Jayasundara, J.M.N.P.; Jayasekara, L.R.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Fire tolerance capacity of seeds of selected Sri Lankan forest plant species
    (Institute of Biology, Sri Lanka, 2009) Niranjana, D.A.A.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
    Floral biology and breeding system of Osbeckia octandra (L.) DC.
    (Institute of Biology, Sri Lanka, 2012) Daranagama, D.A.N.D.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
    Floral biology of Hibiscus furcatus in relation to pollination
    (Institute of Biology, Sri Lanka, 2011) Premathilaka, H.P.P.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
    Histochemical aspects and in-vitro germination of pollen of Rhizopora species
    (Institute of Biology, Sri Lanka, 2010) Gunawardene, D.T.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
    In-vitro and in-vivo Seed Germination Percentage of Typha angustifolia
    (International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Madushani, K.P.K.; Amarasinghe, M.D.; Ratnayake, R.M.C.S.; Dahanayaka, D.D.G.L.
    Typha is a cosmopolitan genus and T. angustifolia is considered an alien invasive plant species in Sri Lanka. Extensive distribution of T.angustifolia is observed in Bundala wetland complex during the recent past. Seed germination is an important process that contributes to plant distribution and invasiveness. Therefore, this study aimed to investigate the in-vitro and in-vivo seed germination of T.angustifolia seeds to evaluate the percentatge seed germination of Typha seeds. Typha seeds were collected from Bundala wetland complex, Hambantota, Sri Lanka (6°12′50″N; 81°13′30″E) during the South West monsoon windy season (seed dispersing period). Typha seeds were cleaned with distilled water and settled in distilled water to select the most viable seeds, which sink to the bottom of the container, whereas non-viable seeds float. Seed viability was tested by placing 50 seeds on cavity slides with 3% 2,3,5-triphenyltetrazolium chloride (TTC) solution and percentage seed viability was calculated after incubating in dark for 8 hours. For the seed germination test, 50 seeds were placed on a layer of Whatman grade no. 1 filter paper (pH 7) in 90mm petri dishes and watered weekly. Seed was counted as germinated when the radical reached 2 mm. For seedling emergence test, 50 seeds were sown in lagoon soil in trays at 0.5 cm depth, which were collected from Bundala wetland complex and they were weekly irrigated with distilled water. A seedling was considered emerged when the hypocotyl was fully erect. All tests were replicated 5 times. Finally the percentage seed germination and percentage seedling emergence were calculated. Results indicate that there is a significant difference (p<0.05) between seed viability in TTC test and seed germination in petri dishes/ seedling emergence in soil trays. TTC test resulted in 87.2±7.2% seed viability, but only 51.2±2% of seedlings germinated in soil trays. Seedlings were emerged after 2 to 3 weeks of sowing. However radicals were failed to appear in petri dishes. Therefore, results conclude that even though T.angustifolia bear numerous viable seeds they show moderate percentage seed germination in wetland soils. It may be due to seed dormancy and further investigations are recommended to evaluate the effect of seed dormancy on distribution of T. angustifolia.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Lesson 21: Weeds and Weed Management Methods
    (Research Services Centre, Faculty of Science, University of Kelaniya, 2015) Senanayake, S.P.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Optimization of DNA extraction protocol and DNA barcoding of Hedyotis quinquinervia in Sri Lanka
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Gunarathne, A.; Attanayake, R.N.; Ratnayake, R.M.C.S.
    Hedyotis quinquinervia, has been identified as a critically endangered possibly extinct (CR(PE)) endemic plant by the National Red List 2012 of Sri Lanka. However, in 2014 it was rediscovered from Thotupolakanda montane forests. It has a high potential as an ornamental plant due to compact, mosaic arrangement of curved shiny leaves with prominent veins. Thick leaf cuticle of this plant, hindered the extraction of good quality DNA for barcoding. Therefore, the aim of the present research was to establish an efficient DNA extraction protocol for H. quinquinervia in the absence of liquid N2. H. quinquinervia leaves were stored at -80 °C or in silica gel for 48 hours prior to the DNA extraction. Three DNA extraction protocols were tested and agarose gel electrophoresis and spectroscopic method were used for the evaluation of quality and quantity of extracted DNA. All the extracted DNA samples were subjected to Polymerase Chain Reaction (PCR) for the amplification of nuclear rDNA-ITS region for barcoding. Out of three methods, classical CTAB protocol with 0.2% β-mercaptoethanol and 2% polyvinylpyrrolidone in CTAB buffer was successful, only after removing the cuticle of the adaxial surface of the leaf. The cuticle removal was achieved simply by using a clear tape and it was confirmed by staining the clear tape with safranin and observing it under the microscope. No DNA extraction was successful with the cuticle present on the leaves. PCR amplification was successful from the extracted DNA and rDNA-ITS sequences were obtained. A sequence of 435 bp, exhibited 98% query cover and 100% identity to H. quinquinervia of the NCBI database. Sequences were deposited in the GenBank under the accession numbers MT373692 and MT373691. It was also found that with the removal of cuticle, the amount of leaves required for good quality DNA extraction was five times less than that of the leaves with cuticle. Modified CTAB buffer and the cuticle removal from fresh leaves of H. quinquinervia were quick and easy modifications to obtain good quality DNA in the absence of liquid N2. Cuticle removal method using clear tapes and the storage at -80 ℃ prior to DNA isolation could be recommended for identification of H. quinquinervia and other plant species with thick cuticle layers on the leaves.
  • Thumbnail Image
    Item
    Pollination and seed biology of Hibiscus furcatus
    (Institute of Biology, Sri Lanka, 2011) Premathilaka, H.P.P.; Ratnayake, R.M.C.S.
  • Thumbnail Image
    Item
    Soil fertility status in five vegetation’s in an abandoned agriculture land in Sri Lanka
    (University of Kelaniya, 2000) Ratnayake, R.M.C.S.; Jayasekara, L.R.