http://ir.lib.ruh.ac.lk/handle/iruor/7513 2026-04-26T20:27:28Z 2026-04-26T20:27:28Z Ferdous, Jannatul Islam, W. Parween, Selina http://ir.lib.ruh.ac.lk/handle/iruor/7985 2024-10-23T06:55:26Z 2017-06-13T00:00:00Z

EFFECT OF TWO CHITIN SYNTHESIS INHIBITORS ON THE REPRODUCTIVE POTENTIAL OF TWO SUCCESSIVE GENERATIONS OF Tribolium castaneum (Herbst) Ferdous, Jannatul; Islam, W.; Parween, Selina Triflumuron and Diflubenzuron, two chitin synthesis inhibitors (CSIs) showed contact activities against T. casta neum. Low concentrations of these compounds significantly decreased the rates of egg laying and egg hatching in two successive generations. Diflubenzuron was found to be more effective and at a concentration of 0.05 ppm it totally stopped egg laying of the treated females. The results suggested that both the CSIs are potent candidates for controlling the population of Tribolium beetles in the stored grains and cereals. Quite low concentrations of these compounds can be used as a surface treatment for the control of insect pests of the stored products.

2017-06-13T00:00:00Z Chen, Xiao-Lu Nilanthi, Dahanayake Yang, Yue-Sheng Li, Dong-Liang Zhang, Jun-Jie Chen, Rong Wu, Hong Li, Qing-Ling http://ir.lib.ruh.ac.lk/handle/iruor/7961 2024-10-21T06:41:15Z 2017-06-15T00:00:00Z

INDUCED POLYPOIDY UNDER IN VITRO CONDITIONS AND HIGHLY EFFICACIOUS SCREENING OF HEXAPLOIDS IN PURPLE CONEFLOWER (Echinacea purpurea (L.) Moench) Chen, Xiao-Lu; Nilanthi, Dahanayake; Yang, Yue-Sheng; Li, Dong-Liang; Zhang, Jun-Jie; Chen, Rong; Wu, Hong; Li, Qing-Ling Leaf, petiole, and root explants from in vitro maintained triploid purple coneflower plantlets were treated with120 mg·L-1 colchicine for the induction of hexaploid plants. Best result for induction of hexaploid was obtained by treating the triploid root explants with 120 mg·L-1 colchicine for 25 days. Regeneration of adventitious buds from the triploid root explants on Murashige and Skoog (MS) medium with 6-Benzyladenine (BA) and Naphthalene acetic acid (NAA) after the colchicine treatment persisted for a time longer than from those untreated. Only slow growing plantlets in a same genotype-and-treated population were selected and detected to increase the screening efficiency as well as save time and efforts. Chromosome counting confirmed that most early-regenerating and fast growing buds were triploid, while most late-regenerating and slow-growing buds were hexaploid, screening only those slow-growing regenerated plantlets could increase effectively the hexaploid. In the present study, screening efficiency increased from 21% (detected all plantlets) to 53% (detected only the slow-growing plantlets). On the other hand, hexaploid plants had much larger stomata and more stomatal guard cell chloroplasts. The stomatal guard cell chloroplast number in hexaploid plants has a good linear relationship with those in the diploid, triploid, and the tetraploid progenitors. Results indicate that the colchicine-induced hexaploid could be induced and screened out with high efficiency, making this process worth further exploring in other species as well.

2017-06-15T00:00:00Z Ranagalage, A.S. Wathugala, D.L. http://ir.lib.ruh.ac.lk/handle/iruor/7960 2024-11-01T07:51:40Z 2017-06-15T00:00:00Z

ALLELOPATHIC POTENTIAL OF SOME SRI LANKAN TRADITIONAL RICE (Oryza sativa L.) CULTIVARS AGAINST Echinochloa crus-galli L. Ranagalage, A.S.; Wathugala, D.L. eeds reduce rice yield by competing with the crops for light, nutrients and moisture. This competition is aggres sive at seedling stage of the crop. Therefore, weed management at seedling stage is important to ensure higher yield at harvesting. Number of dominant and persistent weeds can be identified in Sri Lankan rice fields. Out of them Echinochloa crus-galli L.(Barnyard grass-BYG) is identified as most troublesome weed in irrigated rice eco systems in Sri Lanka. Weed suppressive ability of rice is widely varied with its cultivar. Therefore an experiment was conducted with an objective to evaluate allelopathic abilities of 30 Sri Lankan traditional rice varieties on growth of BYG using rice/ BYG mixed cultures in trays, double pot technique and a field experiment. RCBD De sign was used for all these laboratory, green house and field experiments. Initially significant (p≤0.05) differences in plant height and dry weight were observed in rice/BYG mixed-cultures relative to BYG mono-cultured controls in tray experiment. Then 8 varieties which showed highest and the variety which showed lowest allelopathic po tential in tray experiment were further tested in double pot technique and in field experiment. Similar results were observed except variety Pokkali. Among the 30 rice varieties, Masuran and Kaluheenati showed greatest inhibitory effects on BYG growth and at field experiment these values were greater than 40% for BYG dry matter accumulation. However, further experiments by extracting allelochemicals should be conducted to conclude these varieties with greater allelopathic potential.

2017-06-15T00:00:00Z Ranasinghe, R.M.S. Mudalige, U.K. Jayasinghe Lokuge, L.D.M.N. Edirisinghe, J.C. Guruge, T.P.S.R. Udugama, J.M.M. Herath, H.M.L.K. http://ir.lib.ruh.ac.lk/handle/iruor/7959 2024-10-28T06:36:33Z 2017-02-20T00:00:00Z

ASSESSING CONSUMER DEMAND FOR FOOD QUALITY CERTIFICATION: CASE OF “HACCP CERTIFIED EGGS” Ranasinghe, R.M.S.; Mudalige, U.K. Jayasinghe; Lokuge, L.D.M.N.; Edirisinghe, J.C.; Guruge, T.P.S.R.; Udugama, J.M.M.; Herath, H.M.L.K. This study was aimed to identify the key food quality attributes that the consumers take into account as they pur chase essential food items, in general, and eggs in particular, and extent to which the provision of information augments the consumer demand for “HACCP-certified eggs”. It uses the attributes categorized in „Caswell‟s Clas sification on Food Quality‟ under different subsets, i.e.: Food safety, Nutrition, Sensory, Value, Process, Text and Cues, and in another classification based on the level of information use by a consumer, i.e.: Search, Experience and Credence to develop the analytical framework. Data were collected from a sample of educated, middle income urban consumers (n=200) from Kurunegala and Colombo districts from March – April 2015 through per sonal interviews carried out with the aid of a structured questionnaire and various flyers designed for the pur pose. The results showed that consumers rank the “Label” (83.5%), “Price” (49.5%) and “Purity” (40%) attrib utes as the most important as they purchase an essential food item; yet, for the case of eggs, “Appearance” (75.5%) ranked the first followed by “Purity” (69.5%) and “Price” (30.5%). This highlights that consumer demand for eggs is mainly decided by Search (e.g. appearance, purity) and Experience (e.g. weight, place of origin) attributes of quality. However, it revealed that product certification, which is used extensively with the food items like meat, fish, sea food and milk to signal the compliance of the product with Credence attrib utes, plays an insignificant role with regard to eggs. The outcome of analysis, overall, suggests that, from a food economics point of view, HACCP-certified eggs is not „value for money‟ for an average consumer as the price pre mium paid for such does not compensate for the marginal benefit obtained thro

2017-02-20T00:00:00Z