Research Symposium-2010

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Browsing Research Symposium-2010 by Author "Alwis, L.M.H.R."

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    Developing a Method to Determine 2,4-D and MCPA in Tea with Derivatization by Gas Chromatography-Electron Capture Detector(GC-ECD)
    (Uva Wellassa University of Sri Lanka, 2010) Chamara, P.G.T.; Jayasundara, M.J.; Alwis, L.M.H.R.; Nagahatenna, D.S.K.
    A gas chromatographic method was developed for the determination of residues two phenoxy acid herbicides. The black tea samples were extracted in methanol: water (8:2) mixture, and then followed by liquid-liquid partition with dichloromethane and water (for 2, 4-dichlorophenoxy acetic acid or 4-Chloro-2-methylphenoxy acetic acid). Then the residues were derived with methanol: sulfuric acid (9:1) mixture and the resulting mixture was further cleaned up by hexane and washed with NaHCO3. The esters were analyzed by a gas chromatography equipped with an electron capture detector (ECD) and they were quantified by the external standard method. The recovery percentages of the spiked samples at 0.05, 0.1 and 1.0ppm for 2,4-D were 0.09225, 0.05775 and 0.05325 respectively. Since the recoveries of the spiked samples at 3 spike levels were all below 70%, it was revealed that the method is not up to the acceptable levels for 2,4-D in according to the quality standards of European Union and Japanese. However, the proposed method can be improved with some modifications of methylating reagent, extraction method and clean-up method to determine pesticide residue in black tea. Key words: 2,4-D, MCPA, Black tea, Electron capture detector
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    Effect of Exgenous Growth Regulators on Seed production of Tomato(Solanum lycopersicon) Variety Thilina
    (Uva Wellassa University of Sri Lanka, 2010) Kumarasinghe, K.A.T.; Karunananda, D.P.; Alwis, L.M.H.R.
    Tomato (Solanum lycopersicon) is widely cultivated vegetable crop having high demand in Sri Lanka. Thilina is a popular tomato variety, but high cost in seed production due to the low seed number per pod. The effect of exogenous growth regulators on stimulation of true seed production in Thilina was studied using Gibberellic acid at 350 ppm and Cycocel at 1500 ppm. The level of the Gibberellic acid in flower stalk was changed by applying Gibberellic acid at two different times as two treatments and Cycocel twice as one treatment. Four treatments including control applied within two blocks in' Randomized Complete Block Design. Seed number and germination percentage of seeds obtained were observed and analyzed using SAS package. Results reveal that there was significant difference between treatments. Application of Gibberellic acid once and twice gave higher mean seed number than the mean seed number obtained from the other treatment and the control. Application of Cycocel and control gave lower mean seed number. There was no significant difference between application of Gibberellic acid once and twice. A significant difference was observed between application of Gibberellic acid and control. Application of Gibberellic acid once was the best treatment to increase the seed number of Thilina variety. Application of Gibberellic acid once was adequate to stimulate the increase of the seed number per fresh tomato fruit. Therefore application of Gibberellic acid twice to increase seed number was found to be a waste. The germination of the seeds obtained from all four treatments were more than 80% and results reveal that there was no effect on seed germination by application of Gibberellic acid and Cycocel to increase the seed number in tomato fruits. Key words: Tomato, Growth regulators, Flower stalk, Seed number, Gibberellic acid, Seed germination