Botany
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/3747
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Item Soil aeration as an ecological factor governing mangrove zonation(Springer-Netherlands, 1993) Jayasekera, R.; Lieth, H.The growth of both Rhizophora mangle L. and Rhizophora mucronata Lamk. in saline sand was highly promoted by flooded, reducing conditions in comparison to drained, aerobic conditions, showing the strong tolerance of Rhizophora seedlings to waterlogging and salinity. Under well-drained conditions, both shoot and root systems of the plants showed strongly retarded and reduced growth and a profound inverse proportionality was also found between root growth and pot volume; roots of both species were distorted and showed lack of capillary rootlets. The morphology of the root systems was greatly affected by the culture conditions providing evidence for the ecological adaptability of the Rhizophora root system to a wide variety of environmental conditions. The results obtained are in good agreement with their position in the lower, flooded zone of natural mangrove communities.Item Interelement correlations in the mangrove, Rhizophora mangle L.(Springer-Netherlands, 1993) Jayasekera, R.; Lieth, H.Assuming linear relationships between elements, some significant interelement relationships were detected in Rhizophora mangle grown over a salinity gradient. Sodium (Na) had a clear antagonistic effect on the uptake of potassium (K), whereas the uptake of chromium (Cr) and arsenic (As) seemed to be stimulated by sodium ions. A positive relationship between leaf carbon content and sodium concentration was also found. A significant negative correlation was found between the chemically related two elements, rubidium (Rb) and caesium (Cs). Owing to the competition with the absorption of K+ and NH+ 4 a negative relationship between nitrogen (N) and potassium (K) was found.Item Effect of available rooting volume on seedling growth(Springer-Netherlands, 1993) Jayasekera, R.; Lieth, H.During the early establishment phase of Rhizophora mangle L. seedlings, a consistent positive relationship between available soil volume (varying from 2-91) and growth rate of Rhizophora manglehas been established under greenhouse conditions. As soil volume increased, root systems were larger and consistently less dense. From the results obtained it may be concluded that for optimal growth of Rhizophora mangle seedlings, the volume of soil per plant should approach that volume associated with the growth of the plants in natural habitats. Root volume appears to be a very significant index of plant growth, even under saline, flooded conditions.