Botany
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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.Item Utilization potential of Annona glabra leaf and seed extracts as organic liquid fertilizer for Raphanus sativus(Sri Lanka Foundation Institute, 2015) Kahagalla, T.H.; Ratnayake, R.M.C.S.Annona glabra commonly known as Pond Apple is an invasive tropical fruit tree which grows in wetlands in Sri Lanka. Its seedlings carpet the banks of watercourses, preventing other plant species from germinating and growing. Hence, it replaces the native vegetation and poses threats to the survival of native plant communities. Because of its higher growth rate, A. glabra is an excellent source of biomass and hence this study aimed to identify utilization potential its biomass as organic fertilizer. Oven dried powdered leaves of Annona glabra, Pongamia pinnata, Moringa oleifera and seeds of A. glabra (100 g each) were digested separately for two weeks with 600 ml cow urine with frequent agitation. Commercial fertilizer (Maxicrop) and distilled water were used as a standard and a control respectively. Nutrient contents of all filtrates were analyzed for total nitrogen (Kjeldhal method), total phosphorus (Molybdo- vandate method), potassium, magnesium, calcium, zinc and iron contents (Atomic absorption spectrophotometer). Foliar applications of 1:15 diluted extracts to radish (Raphanus sativus) were done in completely randomized block design with six replications at twice a week for 6 weeks in Mirigama. Shoot height, number of leaves, leaf area, and fresh and dry weights of shoot and root biomasses of R. sativus were determined for all treatments. The data were analyzed using the MINITAB R16 statistical package and ANOVA. Soil pH and organic carbon contents of the study site were 5.98±0.37 and 6.32% respectively. Nutrient contents of A. glabra leaf extract (total nitrogen: 4452.0 mg/L, total phosphorus 1181.5 mg/L, potassium 3079.1 mg/L) and seed extract (total nitrogen: 2311.0 mg/L, total phosphorus 1447.5 mg/L, potassium 2658.8 mg/L) were determined. Application of both A. glabra leaf and seed extracts to Raphanus sativus showed significantly higher (p<0.05) growth performances of shoot height (29.62±1.744 cm), root length (14.3±0.054 cm), fresh shoot weight (75.33±7.49 g/plant), fresh root weight (21.33±7.97 g/plant) and dry shoot weight (30.4±0.38 g/plant) than commercial fertilizer, Pongamia pinnata and Moringa oleifera leaf extracts. In conclusion, combine application of A. glabra leaf and seed extracts is better than that of the other leaf extracts for growth and yield enhancement of R. sativus. As a results of an increase in the urban demand for organic horticultural products, study of uses of A. glabra extracts for the other crops are of great importance.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.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.Item Influence of Chromolaena odorata leaf extracts on seed germination, seedling growth and growth performance of Abelmoschus esculentus L. (Okra) and Vigna unguiculata L. (Bushita)(Institute of Biology, Sri Lanka, 2015) Rathnayake, V.W.; Ratnayake, R.M.C.S.Item Comparative study of Pongamia pinnata, Annona glabra and Moringa oleifera extracts on growth performances of Basella alba L. (Spinach)(Institute of Biology, Sri Lanka, 2015) Kahagalla, T.H.; Ratnayake, R.M.C.S.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.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.Item Pollination and seed biology of Hibiscus furcatus(Institute of Biology, Sri Lanka, 2011) Premathilaka, H.P.P.; Ratnayake, R.M.C.S.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.