Mphil

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    The acclimatization potential of selected ornamental foliage house plantsto contrasting light environments
    (University of Peradeniya, Sri Lanka, 2006) Beneragama, C. K.
    'Low maintenance' has become one of the key issues among present day ornamental plant growers. IT quality of plants, primarily aesthetics, could remain unaffected under variable environmental conditions, such plants can be deemed as low maintenance plants". Therefore, this study was conducted to investigate (he acclimatization potential of six ornamental foliage house plant species to variable light environments. Dracaena sanderiana "Gold", Dracaena sanderiana 'Victory". ('odiaeuni variegatitm "Pictum". Polyscia Jitlicifolia, Scindttpsus aureus 'Lime* and Ophinpogon intermedins variegatwn were the plants used in the study. Plants were exposed to lour contrasting light environments: full sun. Green shade net ( 15 % shade). Black shade nets of 50 % and 80 % for a period of 100 days. Results revealed that plants alter their morphology and physiology in order to survive in stressful light environments, higher irradiances in particular. These alterations were particularly observed in leaf and shoot architecture, which are of vital importance in foliage plants, thus most of the morphological changes were of commercial interest. Pour of the species tested, namely Dracaena 'Gold', Dracaena 'Victory', Codiaeum and Ophiopogon were able to maintain their quality at a commercially acceptable level irrespective of the light environment. Nevertheless, Sc'mdapsm and Polyscia displayed lower acclimatization potential to higher irradiance levels. Other species were able to achieve the acclimatization, about 60 days after the exposure to variable light environments. Ophiopogon was found promising specifically under the green shade nets. Most of the plant responses under the green net (15 % shade) were analogous to those of under black net (50 % shade), which indicates the effect of light quality, particularly under the green net, on morphological responses of plants.
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    Accumulation of Aflatoxins In rice in relation to processing and storage In Sri Lanka
    (Univeristy of Peradeniya, Sri Lanka, 1984) Vithanage, A. K.
    An extensive survey was done the occur of aflatoxins in parboiled rice and raw rice in major rice producing areas and consuming townships in six selected districts. Total of 485 samples were analysed for aflatoxin B1 and G1 by TLC (thin layer chromatography) or liquid column chromatography. All raw rice samples collected from Colombo, Nuwara Eliya and Jaffna districts were free of aflatoxins while in two other districts, number of toxic samples were less than 10 percent (10%). The highest mean aflatoxin content was observed in rice samples collected from Anuradhapura district. The aflatoxin B1 content in parboiled rice was significantly higher than that of raw processed rice. Preferential infection of parboiled rice by Aspergillus flavus and A. parasiticus was observed, Aflatoxin content in rice produced by commercial parboiling was higher than that of household parboiled rice. As the duration of soaking increased, increasing aflatoxin content was observed while addition of sodium hypochlorite to soaking water appreciably reduced A.flavus contaminations and subsequent aflatoxin content in parboiled rice. Brownish, greenish or mouldy rice with ferm ented odour contained over 1000/ug/kg aflatoxin B1. The clean and odourless samples had aflatoxins below 50/ug/kg of aflatoxin B1 . In all samples aflatoxin B1 content was lower than G1 . The intensity of surface microflora and aflatoxin content in market samples of rice were closely related. Polishing before storage may be helpful in reducing aflatoxin content. However polishing of contaminated rice did not sufficiently reduce aflatoxin B1 levels. Black grains and split grains not only reduced the quality but also carried high aflatoxin content. Hence parboiling process should be adapted in a way not to allow them to split, such as hot soaking suggested by Bandyopadhyay and Roy (1977) or mechanical method used In Rice Processing Development Centre (RPDC), Anuradhapura. Cooking did not reduce the aflatoxin content in rice while removal of buoyant in salt water may assist in reducing it. When hospital records of liver diseases were analysed it was true that there were more cases of liver diseases in I l l males than in females, This was true even in male juveniles. In Kandy 33% of deaths due to liver diseases were young nfales, suggesting the importance of liver toxic substances other than alcohol. Considering the other factors which vary from district to district such as alcoholism, rice consuming pattern, reliability of hospital survey data and educat ional standards of the people, there seem to be a higher frequency of non-alcoholic liver diseases in Kandy and Anuradhapura than in Colombo and Galle.