Browsing by Author "Alakolanga, A. G. A. W."

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    Distribution and accumulation of selected heavy metals in Tea plants
    (Uva Wellassa University of Sri Lanka, 2015) Fernando, W. W. A. S. N.; Alakolanga, A. G. A. W.
    Tea (Camellia sinensis (L.) O. Kuntze) is the mostly consumed beverage in the world after the water. Currently, as a natural beverage, its demand is increasing drastically all over the world. But, with the reporting of contamination of tea from different hazardous (Heavy metal, pesticides…etc.), which cause adverse health consequences to human being, the attention for food safety regulations are being promoted by the different counties to protect their people. As a result different quality assurance and food safety regulations and certifications such as ISO, HACCP, GAP, MRL, Acceptable limits for heavy metals …etc. have been introduced to the tea industry also. At field level due to usage of agricultural fertilizers and pesticides, migration of contaminants into a non-contaminated land as vapors and leach through soil, or as dust, or spreading of sewage sludge…etc cause to contamination of tea from above mentioned hazardous. Among them, contamination of tea from heavy metals has a critical issue. According to Sri Lanka Tea Board Standard acceptable limits for Fe - 500, Cu – 100, Pb – 2, Zn – 100 and Cd – 0.2 mg/kg and each country sets its own allowable limit for heavy metal in made tea. Hence, this research was carried out as a primary study to find out the how those heavy metals are being (zinc, copper and lead) distributed and accumulated in tea plants and the impact of Glyphosate application for distribution and accumulation of those heavy metals. The ability of plants to tolerate and accumulate heavy metals can be assessed using Translocation factor (TF) which is defined as the ratio of metal concentration in the shoots to the roots ([Metal] Shoot/ [Metal] Root). Hence, Translocation factor was calculated for each treatment and metal also. Material and Methods Experimental unit were 18 months old tea plants (TRI 4052) which were planted in pots and for 45 days experiment was carried out in a shade house of Uva Wellassa University, Badulla. Research design was Complete Randomized Design. Control (Distilled water), Glyphosate (20 µl per pot) and heavy metal mixture (Zinc 300, copper 300 and lead 200 mg/kg per pot) were applied to plants diluting in 500 mL distilled water as treatments. Number of replications were five. Concentrations of Zn, Cu and Pb were determined in shoots, mature leaves, stem, mature roots and feeder roots using Atomic Absorption Spectroscopy after digested them. Plant tissues were digested using wet digestion procedure, thoroughly washed (from the tap water and distilled water) tea plant parts were dried at 80 C overnight. They were ground and sieved through 1 mm mesh. 0.5 g of sample placed in a small beaker and 5 ml of Con. HNO3 was added. Then, it was kept for overnight to digest the organic compound in plant materials. Digested samples were heated on hot plate at 100 C for three hours (until emission of NO2 fumes has ceased). Each sample was diluted with 25 ml of distilled water and filtered through filter paper. Filtered transparent solution were analyzed using Atomic Absorption Spectrometry. Result and Discussion There was a significant difference (p< 0.05) between the treatments on accumulation of each heavy metal in different parts of tea plant. The treatment of Heavy metal mixture was significantly
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    In vitro antifungal activity of selected medicinal plant extracts against selected postharvest pathogens in fruits and vegetables
    (Uva Wellassa University of Sri Lanka, 2015) Samarasinghe, S. P. R. R.; Alakolanga, A. G. A. W.; Wickramaarachchi, W. A. R. T.; Kumar, N. S.; Jayasinghe, U. L. B.
    Fungal diseases are a major problem occurred in fruit and vegetable cultivations and during post-harvest life of fruits and vegetables. Application of systemic fungicides is the most common practice for commercial control of most of the post-harvest pathogens. Although synthetic fungicides have provided effective control of major postharvest diseases, their application may be harmful to human health and the environment and they become ineffective after prolonged use (Awoitet al, 2013).There are some natural plant products with antifungal activity against various fungal groups. Those natural compounds can be used to control the post- harvest fruit and vegetable pathogens in environmental friendly manner(Pasteret al., 1995). The current study was conducted to determine the antifungal activity of the leaves of Azadirachtaindica(Neem) and Calendula officinalisLinn(Marigold) and the peel of the fruit of Myristicafragrans(Nutmeg) against post-harvest disease causing Fusariumoxysporum,Rhizoctonia Trichodermaspp. This experiment was conducted at the laboratories of Natural Products Chemistry division of the Institute of Fundamental Studies (IFS), Kandy. The selected plant materialswere collected from the home gardens in Kandy. Plant materials were cleaned well under running tap water and air dried. The dried plant materials were crushed. Each plant powder (50 g) was extracted with hexane,ethyl acetate, methanol and distilled water respectively in a sequential process and the evaporation of solvent using rotary evaporator finished 12 extracts.The fungal cultures were obtained from Pathology Division of Horticultural Crops Research and Development Institute (HORDI), Gannoruwa, which were isolated from fruits and vegetables. The antifungal assay was conducted in 9cm diameter petri dishes. The extracts were dissolved in 10% Dimethyl sulfoxide (DMSO) to prepare 5000 ppm concentration of each extractand the 10% DMSO without plant extracts was used as the negative control. The poisoned food technique (Chutiaet al., 2009) was used to test for the antifungal activity. Plant extracts were mixed with the Potato Dextrose Agar (PDA) medium and poured to the petri dishes. The test fungal groups were inoculated with 8 mm diameter mycelial disc from 7- 10 daysold cultures. The plates were incubated at room temperature and colony diameter was measured after three days. This experiment was conducted by using Two Factor Factorial in Complete Randomized Design and data analysis was done by using Analysis of Variance (ANOVA) in General Linear Model. The mean comparison was done by using Tucky pairwise comparison method at significance level of 5% (α = 0.05) in Minitab 17 software.