Botany
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/3747
Browse
5 results
Search Results
Item Some aquatic hyphomycetes from Sri Lanka(Natural Resources, Energy and Science Authority of Sri Lanka, 1984) Gunasekera, S.A.; Rukmani, M.P.R.Item Multi-laboratory chemical characterization of ecological samples(Springer-Verlag, 1989) Jayasekera, R.; Markert, B.The influence of high concentrations of sodium (Na), chlorine (Cl) and bromine (Br) on the analytical results obtained by means of several modern analytical methods by different laboratories was investigated. The results obtained for the halophytic plants, Aster tripolium and Rhizophora mangle, were compared with that of NBS-Citrus leaves (NBS 1572). With a few outliers no considerable “interference effects” from Na, Cl and Br on the results of other elements were found.Item Seasonal changes in potential net photosynthesis of sun and shade leaves of Fagus sylvatica L.(Elsevier, 1988) Jayasekera, R.; Schleser, G.H.Sun and shade leaves of the deciduous tree, Fagus sylvatica, were investigated for their potential photosynthetic activity during the course of one growing season. During the initial period of leaf development and expansion, sun leaves exhibited relatively higher photosynthetic rates. After full expansion of leaves, shade leaves had a higher activity in potential net photosynthesis until about the end of August. Low diffusion resistance for CO2/O2 and higher activities of photosystems in shade leaves seem to be the main causes of their higher photosynthetic potential.Item Elemental composition of different plant species(Journal of Plant Nutrition, 1987) Markert, B.; Jayasekera, R.Element concentrations in leaves and needles of different plant species (Rhizophora mangle, Astertri‐polium, Vaccinium vitis—idaea and Pinus sylvestris) are presented in the form of element concentration cadasters with reference to their abundance. The concentration cadasters of the two halophytes (Rhizophoramangle and Aster tripolium) show that the elements Na, Cl, Br and Sr occur at high concentrations in halophytes. The changes in chemical abundances of halophytes can be attributed to the extreme habitat conditions, i. e. physiological drought, under which they grow. Certain elements are preferentially accumulated in specific plants, e. g. Mn in Vaccinium vitis‐idaea.Item δ13C - variations of leaves in forests as an indication of reassimilated CO2 from the soil(Springer-Verlag, 1985) Schleser, G.H.; Jayasekera, R.An attempt has been made to evaluate the contribution of soil respired CO2 to the total assimilation of a forest tree, by heeding the 13C-concentrations of CO2 from the free atmosphere and from mineralization processes within the soil respectively. An expression has been derived, according to which the assimilated fraction of CO2 from the soil at a particular height of a tree is given by the δ13C-value of the corresponding leaves, δ13C of atmospheric CO2, δ13C of soil respired CO2 and the physiological state of the leaves expressed as the ratio of total respiration over gross photosynthesis and internal over external CO2-concentration. In the particular case investigated, a δ13C-difference of 5‰ has been determined from bottom to top of a beech tree which results in a CO2 contribution from the soil of about 22% for the lower forest strata, while the total contribution of soil respired CO2 accounts for about 5% of the overall assimilation.