Browsing by Author "Kahagalla, T.H."

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    Germinability and Viability of Pollen of Selected Commercial Dendrobium Hybrids
    (International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Kahagalla, T.H.; Herath, H.M.; Attanayake, R.N.; Senanayake, S.P.
    Dendrobium is one of the highly demanding ornamental orchid genera in Sri Lankan floriculture industry. The assessment of functional quality of the pollinium on the basis of germinability and viability is useful for the development of breeding programs for crop quality improvement and pollen storage protocols in conservation. This research was carried out to determine in vivo and in vitro pollen germinability and pollen viability of eight commercial Dendrobium hybrids (A-H). Percentage of pollen viability was studied by placing crushed pollinia on a cavity slide with 1% 2,3,5-triphenyltetrazolium chloride solution and incubating at dark for 12 hours. Pollinia of Dendrobium flowers were placed on the stigma of the same flower on the second day after opening. After three days, pollinia were stained with lacto phenol cotton blue and percentage of in vivo pollen germination was calculated. In vitro pollen germination of the Dendrobium hybrids was studied in three different media. Pollinia were removed from the anthers on the second day after flower opening and placed in (i) 5%, 10%, 15%, 20% and 25% sucrose solutions and (ii) a semi solid medium containing 10% sucrose, 100 mgL-1 H3BO3, 300 mgL-1 Ca(NO3).2H2O, 200 mgL-1 MgSO4.7H2O, 200 mgL-1 KNO3, 8 gL-1 agar and stigmatic fluid of Dendrobium flower and incubated at room temperature. Pollinia of Dendrobium hybrids A, G and H placed in a (iii) semi solid medium containing 1%, 2%, 3% sucrose, 75 mgL-1 H3BO3 and 0.5%, 1%, 2% agar were incubated at 24 oC, 26 oC, and 28 oC. After 48 hours, percentage of in vitro pollen germination was calculated. Means were compared using one-way ANOVA with Tukey’s pairwise comparison test in IBM SPSS Statistics 22 software. As the percentage values of pollen germination and viability were not normally distributed, the values were transformed to arcsin square root values prior to statistical analysis. There was no significant deference in pollen viability of different hybrids which varied between 94% and 77%. The highest percentage of in vivo pollen germination was found in Dendrobium cultivar D (67%) and there was a significant deference in in vivo pollen germination among the hybrids. Correlation analysis was performed using IBM SPSS Statistics 22 software to determine the relationship between pollen viability and in vivo pollen germination and found that there was no significant relationship (�= 0.237). The percentage of in vitro pollen germination was low and the highest in vitro pollen germination (7.2%) was observed in the semisolid medium containing 1% sucrose, 75 mgL-1 H3BO3, 1% agar and incubated at 26 oC for Dendrobium cultivar H.
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    Study of pollen germination of Dendrobium cultivars
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Silva, W.E.R.; Kahagalla, T.H.; Senanayake, S.P.; Attanayake, R.
    Orchidaceae family includes more than 25,000 species, among which Dendrobium genus is one of the most numerous with over 1,200 species in the world. Orchid pollen is packaged as pollinia in which the pollen grains are bound together by viscin threads in masses for effective pollination. Palynological studies of Dendrobium are more important as orchid pollen cannot be dispersed by wind and carried to the stigma for effective fertilization but is mostly done by insects and human beings (hand pollination). Thus, this study was aimed at comparing the efficiency of in vitro pollen germination and natural pollen germination. In vitro pollen germination of commercial Dendrobium variety ‘Thailand tommy’and ‘Burania jet green’ was evaluated using three liquid media containing sucrose (0, 5%, 10%, 15%, 20%) with 0.01% boric acid medium, BK medium containing sucrose, H3B03 (100 mg/L), Ca(N03)2 (300 mg/L), MgSO4 (200 mg/L), and KNO3 (100 mg/ L) and sucrose solutions. Pollen were collected from newly opened flowers of two Dendrobium cultivars, sown on different media and then incubated at room temperature for 24h and examined under a light microscope (10 x 40). Natural pollen germination on stigmatic fluid of Dendrobium cultivars was evaluated using hand pollinated Dendrobium flowers. The pollinia of Dendrobium cultivars were deposited on stigma of newly opened flowers and after 72 hours the small amount of stigmatic fluid was stained with cotton blue in lacto phenol and observed under a light microscope (10 x 40). Pollen tube elongation equal or greater than the diameter of the pollen was considered as germinated pollen. Highest percentage of mean pollen germination was recorded in 0.01% boric acid containing 20% sucrose medium for both ‘Thailand tommy’ (16%) and ‘Burania jet green’ (12.50%) while the lowest mean germination was seen in distilled water medium in ‘Thailand tommy’ (2%) and ‘Burania Jet Green’ (1.50%) in the in vitro pollen germination process. In natural pollen germination process, the percentage of mean pollen germination on stigmatic fluid of Dendrobium cultivars was 26.6% and the pollen tube was elongated 5 times than the pollen diameter.
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    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.