http://dr.lib.sjp.ac.lk/handle/123456789/756 2026-01-07T06:15:43Z 2026-01-07T06:15:43Z Fernando, P.C.B. Wijeratne, Agra T. Abeysiriwardena, M. http://dr.lib.sjp.ac.lk/handle/123456789/853 2022-02-24T05:35:15Z 1995-01-01T00:00:00Z

Micro-spheres (15 µm-240 µm) in Carbon-arc Soot Fernando, P.C.B.; Wijeratne, Agra T.; Abeysiriwardena, M. Some physical characteristics of spheres contained in the soot of a high temperature carbon arc, are discussed.

1995-01-01T00:00:00Z Wijendra, W.A.S. Ranaweera, S.S. Salim, N. http://dr.lib.sjp.ac.lk/handle/123456789/852 2022-02-24T05:34:23Z 1995-01-01T00:00:00Z

The Effects of Papaya Ringspot Virus Infection on the Nitrogen Metabolism of Carica papaya L.: Part II. Composition of Free Amino Acids in the Leaves Wijendra, W.A.S.; Ranaweera, S.S.; Salim, N. Leaves of mechanically inoculated Carica papaya L. plants with papaya ringspot virus (PRSV) were examined for free amino acids by using paper, thin layer and high pressure liquid chromatography (HPLC) techniques. Seven amino acids: aspartic acid, glutamic acid, serine, arginine, threonine, alanine and glycine were detected by paper and thin layer chromatography and another eight amino acids: histidine, methionine, isoleucine, leucine, lysine, tyrosine, valine and penylalanine were detected by HPLC. A two fold increase in the concentration of serine, alanine, arginine, threonine and aspartic acid was observed in the leaves infected with PRSV. Methionine, valine histidine and tyrosine contents in the infected leaves were decreased but no significant differences were found in the contents of glutamic acid, isoleucine and leucine, These changes were detected in the inoculated leaves as early as three hours of inoculation and same tendency was observed at the later stages of disease development. Similar changes in free amino acids were observed in the field plants naturally infected with PRSV, despite their age and different climatic conditions of growth.

1995-01-01T00:00:00Z Wijendra, W.A.S. Ranaweera, S.S. Salim, N. http://dr.lib.sjp.ac.lk/handle/123456789/851 2022-02-24T05:34:23Z 1995-01-01T00:00:00Z

The Effects of Papaya Ringspot Virus Infection on the Nitrogen Metabolism of Carica papaya L.: Part I. Protein and Non-protein Nitrogen Contents in Leaves Wijendra, W.A.S.; Ranaweera, S.S.; Salim, N. The effects of papaya ringspot virus (PRSV) infection, on protein and non-protein nitrogen contents in the leaves of the host, Carica papaya L. were examined. The protein and non-protein nitrogen contents were affected by the virus, but the total nitrogen content remained significantly unchanged when compared to those of healthy leaves. The changes in the levels of non-protein and protein were first detected in the mechanically inoculated leaves in three hours of inoculation. About one and a half times increase in non-protein and a corresponding decrease in protein nitrogen contents were detected in the inoculated leaves after three hours of inoculation. After 12 weeks of inoculation, a three fold increase in non-protein and a corresponding decrease in protein nitrogen contents were detected in the systemically infected leaves, when compared to those of healthy leaves. Similar effects of PRSV infection were observed in naturally infected field plants.

1995-01-01T00:00:00Z Manage, P.M. Piyasiri, Swarna http://dr.lib.sjp.ac.lk/handle/123456789/850 2022-02-24T05:35:15Z 1995-01-01T00:00:00Z

The Chlorophyll-a Content, Species Composition and Population Structure of Phytoplankton in Randenigala Reservoir in Sri Lanka Manage, P.M.; Piyasiri, Swarna Preliminary investigations of phytoplankton composition their population densities, chlorophyll - a, content and seasonal fluctuation of the phytoplakton were carried out in Randenigala reservoir. Vertical and horizontal sampling was performed at different locations,in three major stations and in eight sub stations at monthly intervals from May to December 1992. The phytoplankton groups in the reservoir belong to Chlorophyceae, Cyanophyceae and Bacillariophyceae. The most abundant taxonamic group in the reservoir was Chlorophyceae and the Straurastrum limneticum was the most prominent species. When the vertical distribution was concerned, the highest phytoplankton density was observed in the surface epilimnetic waters upto about 10m depth and it declined with increasing depth.Fluctuation of seasonal phytoplankton densities and production of phytoplankton pulses ofCosmarium species andstraurastrum species were observed during May to June and September to October 1992.The highest chlorophyll - a content was recorded in May and it remained at a low level bellow 0.1 ug/l through out the investiga tion period. During _some occasions there was no clear-cut inverse relationship between chlorophyll a content and transparancy values of the reservoir. The species diversity, high transparancy values and low nutrient conditions of Randenigala reservoir indicates that its trophic nature is perhaps far from eutrophic status.

1995-01-01T00:00:00Z