Browsing by Author "Senanayake, R. A. S. P."

Now showing 1 - 7 of 7

Assessing the suitability of treatments for successful karyotyping of selected Phalaenopsis cultivars
(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Thathsarani, Y. K. D. D.; Senanayake, R. A. S. P.
Orchidaceae is considered as one of the largest flowering plant families and has acquired the attention of researchers in different aspects i.e., taxonomy, phylogeny, phytogeography, etc. In the family Orchidaceae, the genus Phalaenopsis has been attracted the eye of the global floriculture industry due to its specific commercial traits. Therefore, this genus has obtained a significant proportion of the global market as both pot plants and cut flowers. Hence, it is important to develop hybrids with specific commercial traits to meet the demand. Generally, the gene-trait interaction is the key point of the development of hybrids. Consequently, it is important to understand the chromosome morphology and the correlation between the chromosomes and the floral characteristics. Therefore, karyotyping based on modern and classical cytogenetic approaches in Phalaenopsis cultivars would reveal significant information associated with gene- trait interaction. However, the knowledge gap in chromosome characters of Phalaenopsis cultivars has hindered the development of quality improved cultivars with attractive traits. Therefore, it is important to infer the relationships of karyotypes with the chromosome characteristics and the ploidy levels of selected commercially valuable Phalaenopsis cultivars grown in Sri Lanka. Furthermore, it is important to assess the suitability of treatments for successful karyotyping. In this study, potted plants and tissue cultured specimens of four Phalaenopsis cultivars were selected, based on consumer demand. Tissue cultured specimens were obtained from the Floriculture Research Center, University of Kelaniya. The squashing method with 2 mM 8-hydroxyquinoline pretreatment at 3 different temperatures (16 C, 18 C and 20 C) for 4 hours was used in chromosome preparation at mitotic division stages of the root tip cells. Both Feulgen staining and aceto-orcein staining were used as staining protocols in chromosome spread preparation. In chromosome spread preparation, tissue cultured specimens performed better than the specimens of potted plants. Pretreatment with 2 mM 8- hydroxyquinoline at 18 C followed by aceto-orcein staining was successful for tissue cultured white Phalaenopsis cultivar in obtaining chromosome spreads at mitotic metaphase. Hence, pretreatment of tissue cultured plants with 2 mM 8-hydroxyquinoline at 18 C and aceto-orcein staining can be suggested as suitable treatments for successful karyotyping of white Phalaenopsis cultivars.
Effect of edible sugar on in vitro growth and organogenesis of Dendrobium bigibbum x Dendrobium Thailand Black
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Amarasinghe, V. L. P.; Panapitiya, P. D. D. M.; Leelarathne, N. D. C. S.; Priyadharshan, A I.S.; Senanayake, R. A. S. P.
The most popular propagation method of Dendrobium is in vitro micropropagation. However, using laboratory-grade sucrose as the carbon source in micropropagation is expensive for small- scale producers. Present study is aimed to assess the performance of edible sugar as an alternative carbon source to develop an effective, low-cost medium. Protocorm like bodies (PLBs) and plantlets of Dendrobium hybrid (Dendrobium bigibbum x Dendrobium Thailand Black) were cultured on basal MS medium containing different concentrations of sugar; 0.0, 15.0, 30.0, 45.0, 60.0, 75.0 and 90.0 g/L, (T1-T7). A modified MS medium (T8) containing sugar (30.0 g/L), BAP (2.5 mg/L) and NAA (0.5 mg/L) was also used to determine whether there is a comparable effect of sugar individually and when combined with plant growth regulators (PGRs). Growth performance was evaluated in regular intervals. MS medium containing sugar (45.0 g/L) was identified as the best medium for the growth and organogenesis of PLBs resulting in the highest weight accumulation of 20.31 g and 35 plantlets regeneration from 1.00 g of PLBs after two months of incubation. MS medium supplemented with 60.0 g/L of sugar was identified as the most successful medium for the plantlet growth with 17 of mean leaf generation, 33 of mean root generation and an average root length increment of 1.5 cm after four months of incubation. In conclusion, edible sugar can be recommended to use as a sucrose supplement for a cost-effective medium to promote successful in vitro growth and development of the Dendrobium hybrid even with the absence of PGRs.
Growth enhancement of Dracaena fragrans ‘Massangeana’ using Trichoderma species.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Kannangara, S. D. P. S.; Dissanayake, D. M. S. K.; Senanayake, R. A. S. P.
Dracaena fragrans ‘massangeana’ is an ornamental monocot which belongs to the family Asparagaceae, having characteristic shiny green leaves with a yellow streak running down along the center. Although, foliage plant production is considerably large in Sri Lanka, diseases such as Botrytis blight, Fusarium root and stem rot and leaf spot can cause remarkable economic loss to the industry. Plant disease management as well as growth improvement using agrochemicals is not an ecofriendly approach. In this study, an attempt was made to investigate the disease control potential and growth enhancement of Dracaena fragrans ‘massangeana’ using Trichoderma spp. as soil amendments. Soil samples were randomly collected from Randenigala forest reserve in Central Province and Kottawa forest reserve in Southern province and soil fungi were isolated using soil plate method. Twelve Trichoderma spp. were isolated from forest soils. Three fast growing isolates were selected and two of them were identified up to the species level as Trichoderma asperellum strain CHI4, and Trichoderma harzianum strain ZWPUEB10 using macroscopic, microscopic and molecular characteristics. In this study, the effect of selected three Trichoderma spp. and two improved growth media [potting mixture (Coir dust: Sand: Top soil: Compost at a ratio of 1:1:1:1) and top soil] on the growth of D. fragrans ‘massangeana’ were investigated. Stem cuttings of D. fragrans ‘massangeana’ were grown under greenhouse conditions in two different potting media [potting mixture (Coir dust: Sand: Top soil: Compost at a ratio of 1:1:1:1) and top soil]. Plants were then separately treated with 5ml of spore suspension (1×108 spores/ml) of the three Trichoderma spp. Controls were maintained for each medium by treating the plants with distilled water (5ml). Six replicates were conducted for each treatments using a completed randomized design in the greenhouse. Number of roots and leaves, leaf length and width, lengths of roots, fresh and dry weights of plants of each treatment were evaluated as growth parameters. The data obtained for each parameter for D. fragrans ‘messengeana’ were analyzed using Tukey’s multiple comparison with 95% confidence level using MINITAB (version 16) statistical software package. Potting mixture, treated with Trichoderma asperellum showed significantly higher growth rate as well as high foliage quality. Plants grown in potting mixture showed a significant increment in growth when compared to that in top soil. The findings suggest that Trichoderma asperellum can be used as a growth promoter of Dracaena fragrans‘massangeana’ in potting mixture (Coir dust: Sand: Top soil: Compost at a ratio of 1:1:1:1). Regular measurements for color of the leaves, disease incidence and severity were taken for 6 weeks at 7 day intervals to detect any symptoms of diseases development. Disease symptoms were not observed in plants treated with Trichoderma asperellum when compared to other treatments.
Morphological characterization and bioactive properties of selected legumes
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Sovis, W. R. K.; Senanayake, R. A. S. P.
Legumes are nutritionally valuable, as a source of proteins with essential amino acids, dietary fibre and complex carbohydrates while low in fat. Therefore, it is important to develop quality improved species that are resilient to climate change, tolerant to adverse abiotic & biotic factors and with high productivity, for the effective utilization of legumes as food crops. Wild relatives of crops are containing a wealth of important traits due to their adaptation to a diverse range of habitats. However, scarcity of information on phenotypic variability and phytochemical properties of these crop wild relatives have hindered the establishment of quality improved legumes. Therefore, the objective of the study was to interpret the relationships of the selected legume species of Vigna, Phaseolus, Mucuna, Canavalia and Lablab using morphological and chemical characterization and, evaluation of their antioxidant properties. Specimens of fresh plant parts of Vigna radiata (S: Mung, E: Green gram), Vigna unguiculata subsp. sesquipedalis (S: Polon mae, E: Asparagus bean), Mucuna pruriens (S: Wanduru mae, E: Velvet bean), Phaseolus vulgaris (S: Butter bonchi, E: Butter beans), Phaseolus sp., Phaseolus lunatus (S: Pothu dambala, E: Lima bean), Lablab purpureus (S: Halmassan dambala, E: Hyacinth bean) and Canavalia ensiformis (S: Awara, E: Jack bean) were collected from different localities, in Sri Lanka. Selected legume species were characterized using 16 qualitative and quantitative morphological descriptors. Cluster Analysis (CA) was performed to derive phenetic relationships among the species and a clear variation was observed with respect to the important phenetic traits. Total seed protein content was estimated using Lowry assay and Total Phenolic Content (TPC) of seeds was estimated using Folin Ciocalteu method while Total Flavonoid Content (TFC) was estimated by aluminum chloride colorimetric assay. 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay was used to evaluate the antioxidant properties of seeds. Significant difference was observed in the total protein content, TPC, TFC, and antioxidant properties of the seeds of selected legumes. M. pruriens exhibited a comparatively high total protein content (46.82 ± 1.58 mg/g), TPC (40.75 ± 1.74 mg GAE/100g), and TFC (11.76 ± 0.38 mg RE/g) in seeds. L. purpureus showed the highest mean % radical scavenging activity (91.42 ± 0.65). M pruriens, followed by V. unguiculata subsp. sesquipedalis contained a high amount of phenolics and flavonoids in the seeds. Findings suggests that, M. pruriens can be used as a good protein source in human diet due to high total protein, phenolics, flavonoid contents and antioxidant activity. However, due to heavily haired pods and pubescence plant parts M. pruriens is less popular among consumers as a food crop. Therefore, the derived knowledge on morphological relationships can be used in designing breeding strategies for future crop quality improvement programmes to establish cultivars with better consumer preference by eliminating non favored features.
Optimizing growth conditions for vegetative propagation of Near Threatened (NT) epiphytic Cactus Rhipsalis baccifera sub sp. Mauritiana (DC.) Barthlott. (Cactaceae)
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Senanayaka, S. G. M. S. D.; Ratnayake, R. M. C. S.; Senanayake, R. A. S. P.; Attanayake, A. M. A. S.
The Cactaceae family exhibits a diverse range of adaptations, making it popular among horticulturists and Cactus growers. Rhipsalis baccifera sub sp. mauritiana (DC.) Barthlott., an epiphytic cactus, is valued both as an ornamental plant and a medicinal plant. As it is categorized as a “nearly threatened species” (National Red List, 2020) steps must be taken for conservation. Prior studies have not determined the use of commercial growth hormones, the use of naturally available growth media such as compost, soil, and wood, and the effect of shade to increase the successful establishment of stem cuts. We hypothesized that there is an effect of growth hormones, media type and shade level on the growth of the plant. Therefore, this research aimed to determine the optimal shade, growth media, and hormone combination for the vegetative propagation of R. baccifera due to the scarcity of information. Freshly plucked twigs of R. baccifera were utilized as explants for vegetative propagation experiments. Six soil combinations that include Compost (Co), Brick Powder (BP) + Powdered Roof Tile (RT) (1:1), Soil (S) + Co (1:1), S + Sand (Sa) (1:1), S + Co + Sa + BP (2:1:1:1), and S + Co + BP (3:3:2) were assessed to identify the most suitable growth medium for vegetative propagation. R. baccifera planted in each combination was grown in shade net houses with the following shade levels (80%, 60%, and 40%) at room temperature for three months. The successful growth media (Co) and 80% shade level were subsequently employed. It included 16 treatments with 10 replicates randomly for each treatment (160 total), incorporating four types of new growth media that include Co as the base component (Co, Co + S, Co + Wood, and Co + S + Wood) and three types of growth hormones (powder form Rapid Root, Clonex®, a commercial liquid fertilizer). The growth hormone level was 0.3% w/w. The control treatment included no growth hormones. Fresh stem cuttings with a few nodes about 6 cm in length were planted in the above media. Watering was conducted once a week over a three-month period. The length of the plant was recorded at the end of each month as the growth increment parameter. Upon statistical analysis (p=0.05), it was found that there was no significant difference between the average growth rate for any growth media type (p≥0.05), and therefore the inclusion of “compost” in any growth media combination resulted in the best growth. Additionally, the powdered growth hormones "Rapid Root" (5.5±0.4 cm) and "Clonex®" (7.2±0.4 cm), proved to be the most effective, compared to the control (0.9±0.2 cm) for stem cuttings (p<0.05). This study successfully identified optimal conditions for the vegetative propagation of R. baccifera sub sp. mauritiana that includes compost as a growth media and powdered hormone types Rapid Root or Clonex® as the growth hormone, at 80% shade. The findings contribute practical insights for the cultivation of nearly threatened species of Rhipsalis baccifera.
Phytochemical screening and antioxidant potential of three underutilized fruit species in Sri Lanka
(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Somasiri, R. P. I. V.; Herath, H. M.; Ratnayake, R, M. C. S.; Senanayake, R. A. S. P.
Syzygium caryophyllatum (L.) Alston. (S: Dan), Cynometra cauliflora Linn. (S: Namnam) and Antidesma ghaesembilla Gaertn. (S: Bu ambilla) are three underutilized fruit species found in Sri Lanka. This research was carried out to determine the phytochemicals and in vitro antioxidant potential in methanol and acetone fresh fruit extracts of the three underutilized species. Methanolic and acetone extracts of edible parts of the ripe fruits were prepared and the presence of polyphenols, flavonoids, tannins and saponins in the extracts was studied using qualitative assays. Then, the total phenolic contents of the fruit extracts were determined by Folin-Ciocalteu method. Gallic acid was used as the standard and the results were expressed as milligrams of gallic acid equivalents per gram of fresh sample (mg GAE/g FW). The antioxidant activities of the extracts were determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Phenolic contents and antioxidant activities of the fruits were statistically analyzed using Two-way ANOVA and compared using Tukey’s pairwise comparison. The qualitative analysis of the extracts of the three fruits revealed the presence of polyphenols, flavonoids and saponins. Tannins were reported only from methanolic and acetone extracts of S. caryophyllatum and acetone extract of C. cauliflora. The highest total phenolic contents were recorded from the acetone extract of C. cauliflora (27.77±0.08 mg GAE/g FW) followed by the methanolic extract of S. caryophyllatum (26.93±0.09 mg GAE/g FW). The phenolic contents of both extracts of A. ghaesembilla were significantly low (2.66±0.01-3.98±0.01 mg GAE/g FW). The methanolic extract of S. caryophyllatum had the highest DPPH free radical scavenging activity (57.52±0.10%) followed by the methanolic extract of C. cauliflora (41.74±0.24%). From the two extracts of A. ghaesembilla, the acetone extract showed the highest antioxidant activity (15.88±0.52%). From the two solvents used to prepare the fruit extracts, methanol was the best for S. caryophyllatum, while for C. cauliflora both solvents would be beneficial. Acetone will be a better solvent to study the phytochemicals of A. ghaesembilla. Revealing the phytochemicals and antioxidant properties of these fruits will be useful for better utilization and commercialization of these fruits in future.
Sea mosses as an alternative solidifying agent for in vitro micropropagation of Dendrobium cv. “Big Jumbo White"
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Lakmali, G. B. T.; Priyadarshan, A. I. S.; Senanayake, R. A. S. P.
Agar is a commonly added agar is not used as a gelling agent but as a solidifying agent to culture media as solidifying agent. However, agar is an expensive ingredient in the preparation of in vitro media and finding alternative sources as solidifying agents would be beneficial to small scale tissue culture production. Sea moss derived from algal species would be a potential source for serving as gelling agent. Therefore, the present study was conducted with the objective of developing a cost-effective in vitro medium for micropropagation of Dendrobium cv. “Big Jumbo White” using sea moss as an alternative gelling agent. Seeds of Dendrobium cv. “Big Jumbo White” were cultured using full-strength of Murashige and Skoog (MS) basal medium for 45 days under in vitro conditions. The initiated Protocorm Like Bodies (PLBs) were separated and used to assess the effectiveness of agar and sea moss as gelling agent on organogenesis. Media series, supplemented with plant growth regulators (PGRs); BAP (2.0 mg/L) and NAA (0.5 mg/L), sea moss; 4.5g/L (T1), 7.0 g/L (T2), 9.5 g/L (T3), 12.0 g/L (T4), 14.5 g/L T5, and agar as conventional gelling agent [8g/L (T6)]. After 60 days of incubation 1g of PLBs were placed to produce plantlets of Dendrobium cv. “Big Jumbo White”, then were transferred to six different MS media. Agar (8g/L) was used as the control. The highest shoot regeneration (12 cm) was observed in the MS medium containing 12g/L of sea moss. The data were analyzed using the ANOVA and there was no significant difference between sea moss (12g/L) gelling agent and agar (8g/L). According to the findings, MS medium containing sea moss as the gelling agent was successful in the regeneration of shoots from seed culturing of Dendrobium cv. “Big White Jumbo”. Furthermore, in vitro tissue culture media prepared using sea moss compared with agar has shown a 81 % of cost reduction. In conclusion, sea moss can be recommended as a suitable gelling agent for in vitro shoot generation of Dendrobium cv. “Big Jumbo White”.