Browsing by Author "Daranagama, A."

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Morphological and molecular identification of fungi for their association with postharvest fruit rots in some selected citrus species
(2022) Jayasekara, A.; Daranagama, A.; Kodituwakku, T.D.; Abeywickrama, K.
Purpose: The availability of fresh Citrus fruits is limited by their susceptibility to invasion by microbial pathogens which leads to cause serious postharvest losses. The present study was carried out to isolate and morphologically identify postharvest fungal associations from selected Citrus fruit species (C. sinensis, C. limon, C. crenatifolia and C. medica) and to confirm their identity by molecular characterization. Research method: Postharvest fungal associations of selected Citrus fruit species were isolated, and identification was done based on morphological characteristics. Confirmation of fungal associations was done through phylogenetic analysis of newly generated ITS sequencing data. Further, frequency of occurrence of each fungal isolate was calculated in three different districts in Sri Lanka. Findings: From the morphological and molecular identification, Collectrichum fructicola, Collectrichum gloeosporioides, Lasiodiplodia theobromae, Aspergillus niger and Pestalotiopsis sp. were recorded from C. sinensis. Neofusicoccum parvum, Collectrichum gigasporium and Aspergillus clavatus were isolated from C. crenatifolia. Further, Lasiodiplodia theobromae and L. pseudotheobromae were the only fungal association isolated from C. limon and C. medica fruit species, respectively. It is worthwhile noting that this is the first report of association of the C. gigasporium and Pestalotiopsis sp. from Citrus fruits in Sri Lanka. Research limitations: Since this research was mainly focused on the isolation and identification of the potential fungal associations, pathogenicity evaluation could not be carried out. Originality/Value: Findings of potential disease causative agents in citrus will be valuable for agriculture sector, to adopt and practice effective strategies to minimize postharvest losses of citrus fruits.
Morphological Characterization and Molecular Identification of Stem-end Rot Associated Fungal Species Isolated from ‘Karutha Colomban’ Mango Fruits in Sri Lanka
(The Journal of Agricultural Sciences - Sri Lanka, 2019) Ekanayake, G.; Abeywickrama, K.; Daranagama, A.; Kannangara, S.
Purpose: Stem-End Rot (SER) is one of the most frequently found mango postharvest diseases in many countries including Sri Lanka. Availability of a significantly detailed study on morphological and molecular characterization of the SER associated fungal species is comparatively low. The present study has been carried out considering the above fact. Research Method: SER disease associated fungi were isolated and identification was carried out using morphological characteristics. Identification was confirmed by phylogenetic analysis of newly generated ITS sequencing data using Maximum Likelihood (ML) with RAxML software (Ver.8.2.10). Findings: From the morphological studies it was observed that the fungal isolates SER1, SER2, SER3 and SER6 produced conidia on Potato Dextrose Agar. Both morphological and molecular results revealed that the isolates of SER1, SER4, SER5, and SER6 which were isolated from diseased Karutha Colomban mango fruits with SER (in Sri Lanka) belong to Lasiodiplodia sp., Nodulisporium sp., Xylaria feejeensis and Pestalotiopsis sp. respectively. Both SER2 and SER3 were confirmed as Phomopsis sp. During the present study two new fungal species (Xylaria spp. and Nodulisporium spp.) were also identified for the first time from SER of Karutha Colomban mango fruits. Research Limitations: The pathogenicity of these isolates will be tested in near future, since the study was mainly focused on the isolation and identification of the SER associated fungal species. Originality/ Value: Results of the present study will be very valuable for stakeholders in Agricultural sector, before designing control strategies at post-harvest level in order to minimize the loss and extend the storage life of mango.
Physiological disorders of selected Citrus fruit species in Sri Lanka and their effect on fruit quality
(JOURNAL OF HORTICULTURE AND POSTHARVEST RESEARCH, 2021) Jayasekara, A.; Abeywickrama, K.; Daranagama, A.; Kodituwakku, T.
Purpose: This study was conducted to identify the physiological disorders and their symptoms of selected Citrus fruit species (C. sinensis, C. limon and C. crenatifolia). Furthermore, it was aimed to determine whether physicochemical and sensory properties were affected by physiological disorders. Research method: Citrus fruits with physiological disorders were observed separately for visible changes and characters were recorded and photographed. Moreover, Citrus fruits with physiological disorders were analyzed for physicochemical and sensory properties. Findings: Many physiological disorders were recorded from three Citrus fruit species including chilling injury, sun burn, stem-end rind breakdown, oleocellosis, rind disorder, puff and crease, granulation, wind injury, peteca, fruit splitting and fruit cracking. Based on the overall result of sensory analysis, it can be concluded that most of the physiological disorders in studied Citrus species appear on the peel but not adversely affect the edible internal portion of the fruits. Physicochemical properties of C. limon are not adversely affected by physiological disorders whereas C. sinensis and C. crenatifolia are affected by physiological disorders. Limitations: Availability of selected Citrus fruit species throughout the year is limited due to their seasonality. Originality/Value: This study provides novel information about the physiological disorders of some Citrus species in Sri Lanka and other parts of Asia and a future potential exists in controlling these disorders to provide healthy and quality fruits to the market.
Pretreatments and Cold Storage on the Quality of Minimally Processed Ambarella (Spondias Dulcis L.) and the Mixed Load of Ambarella and Pineapple (Ananas Comosus (L.) Merr)
(University of Kelaniya, 2012) Daranagama, A.; Ediriweera, S.; Abeywickrama, K.P.
Minimally processed ambarella (Spondias dulcis L.) and the mixed load of ambarella and pineapple (Ananas comosus (L.) Merr) stored at 5-7 0C for seven days were evaluated for variation in physico-chemical, sensory and microbiological quality. Samples were treated with sodium chloride, calcium chloride, sodium chloride + calcium chloride, ascorbic acid, citric acid, chitosan or distilled water (control) and packed in polystyrene packages before storage. Pretreatments did not have a significant effect on the physico-chemical properties [titratable acidity (TA), total soluble solids (TSS) and pH] when compared to the control. Sensory attributes such as appearance, colour, odour, flavour, taste and overall acceptability generally declined with time but were within acceptable limits by the end of seven-day storage period. The microbial counts (total plate count and yeast and mould count) for all treatments except for the control were within safe-to-consume limits and Salmonella was not detected in any of the samples by the end of storage period. As pretreatments tested had no significant effect on physico-chemical or sensory properties and maintained low microbial counts, minimally processed ambarella and mixed load of ambarella and pineapple processed this way could be recommended for sale at supermarket chains with cold storage facility as a value added product.