IRSPAS 2017

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    Effect of Croton aromaticus leaf extracts in controlling Crown Rot disease of Embul banana.
    (International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Dilhani, S.; Wimalasiri, S.; Abeywickrama, K.; Kannangara, S.
    Embul banana (Musa acuminata-AAB) is one of the major dessert fruits in Sri Lanka, widely consumed by all economic groups due to its small size and characteristic flavour. Although Embul banana has high potential for export market storage and export of this commodity over long distances is difficult in consequence of postharvest fungal diseases. The most common and serious postharvest disease that affect Embul banana is Crown Rot (CR). Use of synthetic fungicides is the widely used method in controlling postharvest diseases of fruits worldwide. The interest of finding natural bioactive components has increased due to the harmful effects of synthetic fungicides on environment and health. In the present study, antifungal activity of aqueous, hot water and ethanolic leaf extracts of Croton aromaticus in controlling CR disease of Embul banana was investigated in vivo. Embul banana hands (85-days mature) were treated with C. aromaticus aqueous, hot water 100% (v/v) and ethanolic leaf extracts (400 mg/ml) alone or in combination with alum (1%) or distilled water (control) were stored in modified atmosphere packaging at 12-14 0C for 14 days. Each treatment comprised of 4 replicates. In-package gases were analysed on initial day and thereafter up to 14 days. Physicochemical properties (pH, firmness, TSS, TA), sensory properties (peel colour, flesh colour, aroma, flavour, taste, overall acceptability), and Crown Rot disease severity were determined in ripening induced fruits after 7 and 14 days of storage period. Statistical analysis was done using the MINITAB 16 statistical package. Oxygen levels measured were observed to be amaintained at 2.2-4.4% while CO2 levels were maintained at 5.5-8.4% in all packages at the end of 14 day storage period. C. aromaticus ethanolic leaf extract (400 mg/mL) was the most effective extract in controlling crown rot disease of Embul banana compared to aqueous and hot water leaf extracts. Physicochemical properties of Embul banana treated with C. aromaticus leaf extract alone and in combination with alum were not significantly different compared to control except for TSS and TA. Most of the sensory properties were preferred by sensory panelists with score values of above 6 indicating the good quality of samples. C. aromaticus ethanolic leaf extract + alum in combination with modified atmosphere packaging and cold storage could be used as a potential safe way of controlling Crown Rot disease of Embul banana.
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    Formulation and stabilization of Trichoderma spp. in selected carrier materials.
    (International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Botheju, W.S.M.; Hewavitharana, N.,; Kannangara, S.D.P.; Abeywickrama, K.
    Trichoderma spp. are one of the major biocontrol agents which have the ability to act against large numbers of foliar and soil borne pathogens and are eco-friendly good plant growth promoting agents. Present investigation was carried out with an attempt to determine 1) the best organic carrier material in which the viability and antagonistic activity retain for a sufficient duration and 2) optimum temperature at which the product can be stored without losing the viability and antagonistic activity. In the present study, three Trichoderma spp. (T. asperellum, T. harzianum and T. virens) were formulated in three carrier materials - coir dust, saw dust and waste of polished rice, which were rich in lignocellulosic organic compounds, nitrogen and mineral salts. In the preparation procedure, glucose and starch were added as carbon sources and cow dung was also added as a source of nitrogen as Trichoderma spp. require sufficient amounts of carbon and nitrogen sources for their growth and development. Three Trichoderma spp. were then inoculated separately (ten mycelial blocks with 1cm diameter from 7-day old cultures) into the carrier materials in sterilized polypropylene bags aseptically. Each treatment comprised of six replicates. Shelf life of these formulated products were studied along with viability tests, using spread plate method from which colony forming units were observed at three week intervals. Mean values of measurements were statistically analyzed using ANOVA and Tukey’s pair wise test (Minitab 16). Antagonistic activity of three Trichoderma spp. against three post-harvest pathogens (Colletotrichum musae, Fusarium oxysporum, Pestaliopsis microspora) were monitored using dual culture method at room temperature (30°C) and 4°C where growth inhibition was measured. All three types of carrier materials were good media for the formulation of all three Trichoderma species and when reisolated, the highest Colony Forming Units were observed in waste of polished rice formulations, at 4°C; [T. asperellum (6.23 log CFU/g), T. harzianum (5.92 log CFU/g) and T. virens (6.04 log CFU/g)] compared to other two carrier materials. Optimum temperature for the storage of formulated products was 4°C that maintained the viability and antagonistic activity of Trichoderma propagules for 130 days compared to the storage at room temperature. However, the values for CFUs of all three Trichoderma spp. in three carrier materials were slightly reduced after storage at 4°C which was not significant. The growth of all three post-harvest pathogens were inhibited by the three Trichoderma spp. and the inhibition values ranged from 36.5% – 83.6%. Growth inhibition values obtained at room temperature (30°C) and 4°C were not significantly different. Among the cost effective three carrier materials at two different temperatures, waste of polished rice at 4°C was found to be significantly effective in retaining the viability and antagonistic ability of the tested Trichoderma species. This may be due to the presence of optimum C contents (35%), C:N ratio (28.42) and pH (6.7) which enhance the production of sufficient propagules of three Trichoderma spp.