Journal of the Rubber Research Institute of Sri Lanka
Permanent URI for this collectionhttps://dl-rri.nsf.gov.lk/handle/1/1399
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Item The impact of current research on the development of the NR industry(Rubber Research Institute. Agalawatta, 1973) Peries, O.S.Item The control of white root disease in Sri Lanka(Rubber Research Institute. Agalawatta, 1973) Liyanage, G.W.; Peries, O.S.Item Scope of conference(Rubber Research Institute. Agalawatta, 1973) Peries, O.S.Item Studies on the biology of phytophthora meadii(Rubber Research Institute. Agalawatta, 1972) Peries, O.S.; Fernando, T.M.Item Summary and conclusions(Rubber Research Institute. Agalawatta, 1971) Peries, O.S.Item Fungi associated with rubber growing soils in Sri Lanka(Rubber Research Institute. Colombo, 1979) Peries, O.S.; Liyanage, A.De.S.; Liyanage, N.I.S.Item A comparative study of the nutrition of Phytophthora meadii and P. palmivora(Rubber Research Institute. Colombo, 1979) Peries, O.S.; Liyanage, A.De.S.; Dantanarayana, D.M.Item Some biases in the generators of technologies by Rubber Research Institute(Rubber Research Institute. Agalawatta, 1977) Barlow, C.; Peries, O.S.This paper considers the distortion in economic use of resources flowing from the generation of partly inappropriate techniques and technologies. This distortion comes to the situation of smallholdings. As an introduction to the paper some pertinent economics concepts are discussed. A review is made of past research in the major rubber producting countries, and highlights the almost exclusive concentration until recently on techniques and technologies suitable for estate conditions. Some specific examples of bias are reviewed in detail and desirable economic adjustment, in application to the circumstance of smallholdings, are suggested. The examples of major concern involve research on tapping systems, and on planting methods including the specific aspects of tree planting densities, intercropping and wedding. There is also the overall problem that the basic levels of input use on rubber research stations are usually inappropriate to realistic experimentation on the problems of smallholders. It is believed that a better adaptation of available techniques and technologies to the situation of rubber smallholdings can produce substantial economic benefits.Item Studies on the variability and pathogenicity of Rigidoporus lignosus(Rubber Research Institute. Agalawatta, 1977) Liyanage, G.W.; Liyanage, A. De S.; Peries, O.S.; Halangoda, L.White root disease in Hevea, caused by the fungus Rididoporus lignosus (Fomes lignosus) occurs widely in Sri Lanka, In recent years, the severity of the disease has increased alarmingly. One of the factors that could be attributed to the increased incidence of the disease is the virulence of the pathogen. This paper report the results of laboratory experiments on the effects of pH, temperature, light and dark, and relative humidity on a number of isolates, obtained from sites located in different rubber growing areas. The fungus is able to grow over a wide range of temperature with maximum growth being recorded at 30C. All the isolates grew better when kept in continuous darkness except one isolate which grew equally well under both light and dark conditions. There was wide variability in the pH requirements for the growth of the fungus. The virulence of the different isolates was examined using healthy rubber roots under laboratory conditions and rubber seedlings in pot culture. The results show that there are differences in virulences and pathogenicity.