Browsing by Author "Jayasinghe, C.K."

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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.
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.
Check list of rubber diseases presently distributed in the world
(Rubber Research Institute of Sri Lanka. Agalawatta, 2001) Jayasinghe, C.K.
Check list of rubber pathogens in Sri Lanka
(National Science Foundation:Colombo; 47p, 2001) Jayasinghe, C.K.
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.
Corynespora cassiicola:a fungal pathogen with diverse symptoms on Hevea rubber
(Rubber Research Institute. Agalawatta, 1999) Jayasinghe, C.K.; Silva, W.P.K.; Wettasinghe, D.S.
Corynespora leaf fall and future of the leading rubber clones in the world
(Rubber Research Institute of Sri Lanka. Agalawatta, 2002) Jayasinghe, C.K.
Corynespora leaf fall. the most challenging rubber disease in Asian and African continents
(Rubber Research Institute. Agalawatta, 2000) Jayasinghe, C.K.
Corynespora leaf spot disease of rubber (Hevea brasiliensis) - a new record
(Rubber Research Institute. Agalawatta, 1986) Liyanage,. A De S.; Jayasinghe, C.K.; Liyanage, N.I.S.; Jayaratne, A.H.R.
Cross inoculation of Bradyrhizobia among three common legume cover crops in rubber plantations of Sri Lanka
(Rubber Research Institute. Agalawatta, 1989) Jayasinghe, C.K.; Wettasinghe, S.
Mixtures of legume cover crops are common in rubber plantations of Sri Lanka during the immature phase of rubber, and changes in ther composition occure with the changes in environment conditions due to the growth of canopies in rubber plants. Bradythizobial isolates from Pueraria phaseloides and desmodium ovalifolium were able to nodulate both legumes, but non of the isolates, including CB 756 (C.S.I.R.O collection, Queensland) produced nodules on Mimosa invisa.
Cultural characteristics and reproductive morphology of Geotrichum sp.. a guide to distinguish Geotrichum from Rigidoporus microporus
(Rubber Research Institute. Agalawatta, 1998) Jayasinghe, C.K.; Wettasinghe, J.L.P.C.
Culture characteristics of Geotrichum sp. isolate IMI 354411, a fungus responsible for the saprophytic colonization on Hevea roots are described. It was also shown that this fungus could be easily distinguished from Regidoporus lignosus, a devastating pathogens of Hevea roots, by the zonate and cloudy appearence of its colonies on malt agar with a cream undersurface and the disarticulating hyphae which later break upto arthric conidia.
Cylindrocladium leaf spot disease of rubber. a review on the causative agent
(Rubber Research Institute. Agalawatta, 2000) Jayasinghe, C.K.
Cylindrocladium quinquesptatum. cultural characteristics and reproductive morphology of the clove isolate IMI 342173 from Sri Lanka
(Rubber Research Institute of Sri Lanka. Agalawatte, 1996) Jayasinghe, C.K.; Wijesundera, R.L.C.
Cylindrocladium quinquesptatum boeddijn and reitsma, is a destructive pathogen of eugenia caryophyllata (clove) and is identified as a potential pathogen of hevea barasiliensis in Sri Lanka. Further, the fungus infescts a number of ornamental and forest trees. We report using photomicrographs the cultural characteristics abd the morphology of the reproductive structures; condida, vesicle, stipe, phialides, chlamydospores and microsclerotia of clove isolate IMI 342173. Our investigations demonstrates that the isolate IMI 342173 from Sri Lanka resembles the isolates of C. quinqueseptatum obtained from different hosts in other parts of the world.
Diurnal variation in nitrogenase activity of common cover crops in rubber plantations of Sri Lanka
(Rubber Research Institute. Agalawatta, 1989) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.
Diurnal fluctuations in nitrogenase activity (acetylene reducing activity) have been observed in several nitrogen fixing systems. All experimental plants viz. P. phasides D. ovalifolium and M. invisa demonstrated diuanal rhythm withlight intensity. The lowest acetylene reduction activiteswere detected around midnight and they were activelyu fixing nitrogen by 8.00 am. M. invisa responded to high soil temperature in addition to light intensity. A marked drop in acetylene reduction activity was observed by about 4.00pm when the soil temperature was around 38ºC
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 nitrogen
Effect of combined nitrogen on nodule function of leguminous crops with special reference to tropical soils
(Rubber Research Institute. Agalawatta, 1991) Jayasinghe, C.K.
The effect of combined nitrogen on nitrogen fixation has been discussed by several investigators and from their findings it could be concluded that inorganic nitrogen may have either stimulatory, neutral of negative effect on nitrogen fixation depending on the type of legome and soil condition. It was reported in some instances that low levels of combined nitrogen especially when applied as a "Starter" fertilizer at germination, stimulates plant growth and enhances nodule mass and nitrogen fixation. On the other hand when most of the legumes are grown in soil high in available nitrogen, the nitrogen fixation rate is severely affected. This phenomenon may become more critical when legumes are grown as cover crops where non legume counterpart is fertilized with nitrogenous fertilizer. The degree of inhibition appears to vary with sevaral factors vis, concentration of combined nitrogen, host species, cultivar, strain of root nodule bacteria, rate of inculation, light intensity and temperature. However, the most critical factor is the concentration of combined nitrogen and it has been shown that very low concentrations such as 240 ppm N reduced
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.
Effect of incubation time on acetylene reduction activity of common cover crops of Sri Lankan rubber plantation
(Rubber Research Institute. Agalawatta, 1989) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.
A wide range of incubation time from a few minutes to severl hours have been used with defferent plant systems in investigations on acetylene reduction assays. However, the duration of incubation period is of utmost importance in obtaining nitrogen fixation estimates using this technology. Time course experiment showed that acwtylene reduction by nodules of P. phaseoloides and D. ovalifolium started without a lag but rate of the nitrogenasse activity was reduced 4 hours after incubation while M. invisa showed a considerable activity even at the 8th hour of incubation. In the second experiment which was conducted to observe the relationship between acetylene reduction activity and incubation time upto one our, there was a linear relationship for both P. phaseoloides (r = +0.9832) and D. ovalifolium (r = + 0.99961)
Evaluation of the antagonistic effect of different plant species on white root disease causing fungus: Rigidoporus microporus
(Rubber Research Institute:Agalawatta, 2014) Silva, M.K.R.; Jayasinghe, C.K.; Tennakoon, B.I.
First report of Colletotrichum acutatum on Mangiferia indica in Sri Lanka
(2009) Jayasinghe, C.K.; Fernando, T.H.P.S.