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Item Mycoflora associated with Hevea phylloplane(Rubber Research Institute:Agalawatta, 2000) Jayasinghe, C.K.Item Toxic metabolite from clove isolate of Cylindrocladium quinqueseptatum(Rubber Research Institute:Agalawatta, 1999) Jayasinghe, C.K.; Wijesundera, R.L.C.Cylindrocladium Quinqueseptatum Boedijn Reitma causes seedling blight and extensive defoliation on a wide variety of plants and is widely distributed in the humid tropics.It is a serious pathogen of Eugenia caryophyllata in Sri lankaand has been identified as a potential lpathogen on Hevea brasileensis in the eastern Hemispher .All cloveisolates;IMI 342173 (rt),359378(Aw),359379(Rw)and 359380(Kp) of c.quinqueseptatum tested were found to be capable of secreting toxic substances to the growing medium.Toxic culture filtrates proved to be thermostagbl4e(up to 100C)and host specific.The type and the size of the lesions lproduced by the crude toxin of different isolates varied markedly.Isolate,Rt produced the largest lesions (Highest score) indicationg its aggressive nature in toxin production while Aw and Rw isolates showed a mild reaction.When the reaction of Hevea clones towards the crude toxin was considered three main clusters ofclones were distinguished through cluster analysis indicationg the marked variation of Hevea clones grown in the Eastern Hemisphere in their sensitivity to the crude toxin.The possibility of making use of this toxin as a tool in screening Hevea populations for cylindrocladium leaf spot disease has also been discussed.Item Cell wall degrading enzyme secretion by Cylindrocladium quinqueseptatum(Rubber Research Institute:Agalawatta, 1999) Jayasinghe, C.K.; Wijesundera, R.L.C.Cylindrocladium quinqueseptatum causes leaf fall of clove in Sri Lanka and is responsible for the leaf spots of rubber in Malaysia.only one isolate (KP)from four pathogenic isolates examined secreted polygalacturanase(PG) when grown in liquid media.None ofthe isolates secreted pectin lyase(PL).The extracts of clove and rubber leaf tissues,inoculated with the KP isolate did not show any PG and PL activity .The leaf tissue did not have the ability to ingibit c.quinqueseptatum PG produced in culture.All isolates of C.quinquesepltatum secreted cellulases viz.cellobiase and b-glucosidase in culture.cellobiase was detected in the inoculated rubber leaves,The levels of B-glucosidase,an ingerent enzyme of Hevea leaves,also increased rapidly following infection.The results indicate that pectic enxymes play a minimal or no role in disease developmet of C.quinqueseptatum infecton in cloves and Hevea.Thus cellulolyic enzyme probably play a nutritive role.Item Susceptibility of different leaf stages of Hevea to Corynespora cassiicola(Rubber Research Institute:Agalawatta, 2010) Fernando, T.H.P.S.; Jayasinghe, C.K.; Wijesundera, R.L.C.; Siriwardena, D.Item Native root-nodule bacterial populations in rubber growing soils and forest soils(Rubber Research Institute:Agalawatta, 1986) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, A.Item Effect of different levels of supplemental nitrogen on CO2 assimilation rates and productivity of Pueraria phaseoloides (Roxb) Benth and Desmodium ovalipolium (prain) wall. ex ridely grown in agalawatta series soil(Rubber Research Institute:Agalawatte, 1985) Nugawela, A.; Jayasinghe, C.K.; Aluthhewage, R.; Wettasinghe, S.Plant dry matter production is linked to CO2 assimilation rates, respiratory losses and total leaf area. Experiments were undertaken to determine the effect of different levels of supplimental nitrogen given to legume cover crops, on their CO2 assimilation rates and productivity. They were found to be highest for Pueraria phaseoloides and Desmodium ovaliforlium when given around 140 and 35 ppm of supplimental nitrogen. Reciprocal of specific leaf area and laef nitrogen content were also determined and they showed a positive linear relationship with supplemental nitrogen levels. How nitrogen could a influence the CO2 assimilation rates of cover crops studies are discussed.Item Seasonal variations in nodule activity of Pueraria phaseoloides (Roxb) Benth(Rubber Research Institute:Agalawatta, 1990) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.The age of Pueraria phaseoloides plants had a marked effect upon the rate of acetylene reduction in their nodules. Acetylene reduction activity increased with the age of the plant and maximum efficiency of nodule activity was detected 60 days after sowing, followed by a marked decline on the 120th day and continued at a low rate. Dry matter yield and total nitrogen in plants was more or less constant thrugh out the assay period.Item Effect of combined nitrogen on growth and nodule function or Pueraria phaseoloides(Rubber Research Institute:Agalawatta, 1991) Jayasinghe, C.K.; Wettasinghe, D.S.Nodulation and nitrogen fixation rates of most of the legumes are reported to be severely affected when they are grown in soils high in available nitrogen. Furthermore, this phenomenon may become more critical when legumes are grown in multiple cropping systems like Pueraria phaseoloides in rubber plantatons where ono legume counterpart is fertilized with nitrogenous fertilizer. Results of experiments conducted in seeding agar to find the effect of nitrogen on growth and nodule function of P. phaseoloides showed that nodulation of P. phaphaeoloides was inhibited at a concentration between 24.4 and 44.8 ppm nitrogenItem A comparative study of Colletotrichum species causing anthracnose in Hevea(Rubber Research Institute:Agalawatta, 2009) Jayasinghe, C.K.; Fernando, T.H.P.S.; Jayawardana, N.Item Changing scene of the disease scenario of the rubber tree in Sri Lanka. history and current status(Rubber Research Institute of Sri Lanka:Agalawatta, 2009) Jayasinghe, C.K.