Chemistry
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Item Effect of coconut (Cocos nucifera) water extract on the development of adventitious roots in Polyscias fillicifolia stem cuttings(The Journal of Agricultural Sciences - Sri Lanka, 2021) Jayawardena, B.M.; Agampodi, V.A.; Abeywickrama, K.P.Purpose Vegetative propagation continues to be a popular method to propagate ornamental plant species. Coconut water (CW) can be considered as an abundant source of hormones and other plant growth regulators (PGRs). In this study, vegetative propagation of Polyscias fillicifolia was attempted using PGRs isolated from CW. Research method Stem cuttings were treated with varying concentrations (5, 10, 25, 50,100 μg mL-1) of PGR isolated from CW. The results were compared with a control set (treated with distilled water) and with those treated with solutions of pure synthetic indole acetic acid (IAA). Findings P. fillicifolia canes treated with a 25 μg mL-1 concentration of IAA, isolated from CW, showed the highest levels of root induction and development. Root development was more rapid (5 weeks) in the samples treated with PGRs isolated from CW compared to the canes propagated in the field by placing the canes on coir beds in plant nurseries. (6 weeks). Originality This is the first study to use PGRs isolated from CW extracts to improve lateral root proliferation, induce shoot development and leaf emergence in P. fillicifolia.Item Repellency and toxicity of four essential oils to Sitophilus oryzae L. (Coleoptera: Curculionidae)(2004) Paranagama, P.A.; Abeysekera, K.H.T.; Nugaliyadde, L.; Abeywickrama, K.P.Item Foliage preservatives for vase life extension of two dieffenbachia species(2010) Thambugala, S.; Abeywickrama, K.P.; Karunarathna, S.Cut foliage of Dieffenbachia maculata and Dieffenbachia amoena were subjected to continuous treatment with several foliage preservatives and export simulation. The preservatives used were 1.75% of sodium hypochlorite, 5% vinegar and VimTM dish washing detergent. Tap water without any added chemicals was used as the control. The highest vase life of 45.1 days was observed in D. maculata cut foliage when subjected to continuous treatment with tap water. Cut foliage of D. maculata subjected to continuous treatment with 0.016% (v/v) dish washing detergent (Vim™) solution and 0.016% (v/v) sodium hypochlorite (NaOCl) and subjected to export simulation for two days at 12-140 C and 85-90% relative humidity (RH), had relatively longer vase life of 38.9 days and 37 days respectively. Cut foliage of D. amoena had the longest vase life of 21 days when subjected to 0.016% NaOCl treatment and export simulation. NaOCl which is considered as a biocide and mild vinegar solution which is acidic inhibited the bacterial growth in vase solutions increasing the vase life of cut foliage. A Bacillus sp. and a Staphylococcus sp. were associated with vase solutions of D. maculata and D. amoena cut foliage. Treatment with NaOCl and VimTM satisfactorily extended the vase life of cut foliage of D. amoena and D. maculata respectively and could be recommended as preservatives for use during export.Item Effect of Chemical Pretreatments on the Quality of Minimally Processed Pineapple Stored in Polystyrene Packages(2012) Ediriweera, S.; Abeywickrama, K.P.; Latifah, M.Minimally processed pineapple (Ananas comosus L.) cv. Mauritius stored at cold temperature for seven days were evaluated for physicochemical, sensory and microbiological qualities. Pineapple pieces were treated with 1% sodium chloride, 1% calcium chloride, a combination of 1% sodium chloride and calcium chloride, 1% ascorbic acid, 1% citric acid, 0.1% chitosan and distilled water (control) and packed in polystyrene packages before storage. Pretreatments did not significantly affect the physicochemical properties studied. Many sensory attributes in minimally processed pineapple decreased after seven days of storage. However, sodium chloride (1%) and a combination of 1% sodium chloride and calcium chloride pretreatments resulted in maintaining a better flavour in pineapple after a seven day storage period than the rest of the treatments. Microbial counts for all treatments and the control were within safe-to-consume limits while Salmonella was not detected in any sample.Item Wheat crown rot pathogens Fusarium graminearum and F. pseudograminearum lack specialization(2010) Chakraborty, S.; Obanor, F.; Westecott, R.; Abeywickrama, K.P.This article reports a lack of pathogenic specialization among Australian Fusarium graminearum and F. pseudograminearum causing crown rot (CR) of wheat using analysis of variance (ANOVA), principal component and biplot analysis, Kendall’s coefficient of concordance (W), and κ statistics. Overall, F. pseudograminearum was more aggressive than F. graminearum, supporting earlier delineation of the crowninfecting group as a new species. Although significant wheat line– pathogen isolate interaction in ANOVA suggested putative specialization when seedlings of 60 wheat lines were inoculated with 4 pathogen isolates or 26 wheat lines were inoculated with 10 isolates, significant W and κ showed agreement in rank order of wheat lines, indicating a lack of specialization. The first principal component representing nondifferential aggressiveness explained a large part (up to 65%) of the variation in CR severity. The differential components were small and more pronounced in seedlings than in adult plants. By maximizing variance on the first two principal components, biplots were useful for highlighting the association between isolates and wheat lines. A key finding of this work is that a range of analytical tools are needed to explore pathogenic specialization, and a statistically significant interaction in an ANOVA cannot be taken as conclusive evidence of specialization. With no highly resistant wheat cultivars, Fusarium isolates mostly differ in aggressiveness; however, specialization may appear as more resistant cultivars become widespread.Item Quality of minimally processed modified atmosphere sorted bell pepper, as affected by pre treatments(2015) Ediriweera, S.; Abeywickrama, K.P.; Latifah, M.; Othaman, F.; Hussin, R.; Tham, S.Minimally processed bell pepper strips stored at 8-100C for seven days were evaluated for variation in color, in package gases, firmness, physicochemical sensory and microbiological quality. Bell pepper strips were treated with sodium chloride, calcium chloride, sodium chloride+calcium chloride or distilled water (control) and packed in polystyrene packages before storage. Pretreatments did not drastically affect the physicochemical properties (titratable acidity (TA), total soluble solids (TSS) and pH) when compared to the control. A slight discoloration of bell pepper was evident, indicated by decreasing L*, a* and b* values. Variations in firmness were observed. Fair-ly high level of CO2 accumulation was evident inside packages where O2 concentration displayed a declining trend. Sensory attributes generally declined with time but were within acceptable limits. Microbial counts were within safe-to-consume limits for all samples within the storage period. All pretreatments tested had no drastic effect on sensory properties and maintained low microbial counts, however 1% sodium chloride pretreatment was more successful in retaining higher sensory properties and maintaining lower microbial counts by the end of stor-age period than the other pretreatments.Item Isolation and identification of fungi from mushroom composts and evaluation their biological activity(1999) Wickremasinghe, R.; Abeywickrama, K.P.; Abeythunga, D.T.U.Item Root growth promotion of Ficus species during air-layering(2010) Gamlath, M.; Abeywickrama, K.P.; Wickramarachchi, S.Three chitosan concentrations (1%, 3%, 5% w/v) were tested for their root growth promotion properties in air-layering of three popular ornamental Ficus species namely Ficus triangularis, Ficus microcarpa and Ficus benjamina. Subsequently, these treatment responses were compared with a rooting hormone (naphthalic acetic acid) and an organic root promoting extract (Root Most) available in the local market. Tap water was used as the control. Air-layered plants were further subjected to export simulation for 14 days at 12-14 0C and 90% relative humidity (RH) with the aim of lengthening the storage period. 3% (w/v) chitosan treatment concentration was shown to promote the root growth significantly. 3% (w/v) chitosan treatment resulted in the highest mean root length of (15.3 cm) in F. triangularis compared to the 10.3 cm of tap water control. Similarly, highest mean root length of 38.8 cm was recorded for F. microcarpa for 3% (w/v) chitosan treated layers compared to 14.8 cm of tap water treated layers. Further, the highest mean root density of 3.17 was recorded for 3% (w/v) chitosan treated layers of F. triangularis. A cost effective packaging system was developed during this research which could be utilized in cold storage of air-layers during air or sea freight.Item Microbial Status of Fresh Cut Cooking Banana Variety Alukesel (Musa acuminata× Musa balbisiana, ABB Group) as Affected by Pre-treatments(2016) Siriwardana, H.; Abeywickrama, K.P.; Herath, I.Fresh cut (minimally processed) cooking banana variety Alukesel was subjected to different pretreatments, packed in polystyrene packages and stored at 5-7 °C for a week. Effect of several identified pre-treatments on Total Plate Count (TPC) and Total Yeast and Mould counts (TYM) were evaluated. Bacteria isolated from plates were identified using biochemical tests and molecular tools. In pre-treated samples, microbial counts were within safe-to-consume limits. Bacillus cereus, Enterobacter ludwigii and Bacillus thuringiensis were identified from fresh cut samples using molecular tools. Citric acid at 3% w/v effectively controlled bacteria, yeasts and moulds and this observation was significantly different from the control (p<0.05). The present study has shown that 3% citric acid was the most effective pretreatment for minimal processing of Alukesel which controlled bacteria, yeasts & moulds completely. Alukesel pretreated with 3% citric acid was free from food borne pathogens such as Salmonella, Clostridium, Yersinia, and Listeria.Item Growth promotion and preservation of bare rooted plants of Dracaena sanderiana for commercialization(2011) Gunathilake, C.; Abeywickrama, K.P.Bare rooted Dracaena sanderiana is a popular indoor plant with high commercial potential. D. sanderiana top cuttings were dipped in different growth promoting substances and preservatives to obtain disease free bare rooted plants within a short period of time. The six treatments tested included, three concentrations of chitosan, an organic root promoting extract, NaOCl and vinegar. Chitosan 0.002% w/v solution was found to be the most effective rooting substance. Plants grown in this solution had the highest root length (8.7 ± 0.8cm) and highest root number per plant (44.7 ± 2.2). Lowest number of Colony Forming Units (CFUs) of bacteria was recorded from the chitosan 0.002% w/v solution (18. 8 ± 3.3) compared to tap water (control) (233.2 ± 7.7). Considering both preservative and growth promoting effects, chitosan 0.002% w/v solution can be recommended for the production of disease free bare rooted plants within a short period of time.