Browsing by Author "Jayasekera, L.R."

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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.
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.
Leaf flavonoids as chemotaxonomic characters in genus Sida L. (Bevila)
(Tropical Agricultural Research, 2001) Perera, N.I.S.; Senanayake, S.P.; Jayasekera, L.R.
Theflavonoid distribution pattern of five species of genus Sida was studied to identify the species since the existing classification was mainly based on morphological and anatomical characters. Four main flavonoids and one minor flavonoid were isolated by preparatory paper chromatography. Trace amounts of six flavonoids were observed in two-dimensional paper chromatography. The major flavonoid compounds in S. acuta. S. rhombifolia. S. alnifolia. and S. cordifolia were glycosylated and methylated flavonols where as S. humilis had minor flavonoids. There are remarkable variations in the substitution patterns of these flavonol compounds. The presence ofquercetin 3-methyl ether and the compound C is a common character to S. rhombifolia and S. cordifolia. and hence these two species may be considered as related taxa in the genus Sida. Kaempferol glycosides were the major Jlavonoids in the S. alnifolia in contrast to the S. rhombifolia. which was characterised by the presence of methylated quercetin. This is in agreement with the recent revision of the genus in which they are considered as different entities. The habit ofS. humilis. prostrate trailing, is different from other species, which are erect herbs. This dissimilarity of morphology agreed with its characteristic flavonoid pattern of possessing minor flavonoids.
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.
Qualitative phytochemical analysis and phenetic variation of Piper species in Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2015) Jayarathna, S.P.N.C.; Senanayake, S.P.; Jayasekera, L.R.
The genus Piper is represented in Sri Lanka by ten species of which three are endemics. Piper nigrum L. (black pepper) and P. betle L. (betel) are the main crops that make the genus commercially important and some species are used in traditional medicine. This study aimed to reveal the interspecific relationships of selected Piper species based on the variation in qualitative phytochemical screening and phenetic approach. Piper nigrum L., P. betle L., P. longum L., P. chuvya (Miq.) C. DC., P. siriboa L., P. sylvestre Lam. and P. zeylanicum Miq. were collected from natural habitats and from the cultivations. The air dried leaves were powdered using a grinder and subjected to successive extraction using petroleum ether, chloroform, ethyl acetate and methanol. All the extracts were subjected to qualitative phytochemical tests. Anatomical studies were carried out by observing epidermal peels and transverse sections of the fresh leaves and photomicrographs were prepared. The phytochemical screening confirmed the presence of tannins, flavonoids, terpenoids, glycosides, alkaloids and phenolic compounds in all the species examined. Various types of trichomes, glands and secretory cells were present in the leaves which indicates the richness of secondary metabolites. Fourteen morphological and anatomical characters of leaves were subjected to cluster analysis using PAST software to infer interspecific relationships. According to the phenogram (Single linkage, Euclidean distance), P. longum, P. zeylanicum and P. sylvestre were clustered to one group showing more similarities while P. nigrum, P. chuvya, P. siriboa and P. betle were separated from the rest. Presence of non-glandular trichomes, symmetry of the leaf base and leaf length were the most discriminating characters.
Utilization of protease activity of Carica papaya for the hydrolysis of fish waste.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Sathischandra, M.K.D.P.M.; Ranasinghe, R.H.A.A.; Jayasekera, L.R.
This study was undertaken to investigate whether fish waste can be used as a source of nitrogen in agricultural purposes to fulfill plant nitrogen requirements. However, fish waste, being a rich source of proteins should be hydrolyzed first to make nitrogen soluble and available to plants. The objective of the present work was to assess the proteolytic activity of Carica papaya plant parts which are rich in proteases, papain being the major enzyme, for the hydrolysis of fish waste. Crude enzyme extracts were prepared from different parts of C. papaya, i.e. leaves, unripe peel, ripe peel, ripe pulp of the fruits (5 g wet weight/ 20 mL distilled water) and latex (5 g dry weight/ 20 mL distilled water). They were tested qualitatively by milk coagulation test, and quantitatively by universal protease enzyme assay at different temperatures (370C, 550C, 700C and 800C) and pH (2.5, 4, 5.5, 7.5 and 9) to determine the optimal conditions for the enzymatic activity. The amount of hydrolyzed proteins in powdered fish waste was determined by the Bradford method over different incubation periods (1, 2, 5, 24 and 48 hours). Milk coagulation test confirmed the presence of proteases. Latex and ripe pulp resulted in the highest enzyme activities respectively1.22±0.19 and 0. 03±0.05 μmol/mL of crude extract at 550C, while leaves showed the highest activity of 0.66 ± 0.09 μmol/mL of crude extract at 700C, ripe and unripe peel showed the highest activities of 0.19 ± 0.09 and 0.12 ± 0.74 μmol/mL crude extract respectively at 900C. The optimal pH for latex and unripe peel was 7.5 and 5.5 for leaves. Five hours’ incubation of fish waste with latex and leaves, and 24 hours incubation with ripe peel and pulp resulted in significantly higher amount of hydrolyzed proteins. The highest enzyme activity on fish waste hydrolysis was shown by the papaya latex followed by the leaves, ripe pulp and ripe peel. Different parts of C. papaya can be used effectively as a cost effective, potential source for hydrolysis of fish waste protein.