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Coal-smoke emissions affected photosynthesis, N-metabolism and growth characteristics of Triumpfetta rhomboidea, as observed at pre-flowering, flowering and post-flowering stages of plant growth. The net photosynthetic rate and stomatal conductance decreased, whereas intercellular CO2 concentration increased under pollution stress. The amounts of photosynthetic pigments in leaves were consistently less, up to 35% for chlorophylls and 84% for carotenoids. Nitrate level was raised while NR activity and protein contents in leaves declined at the polluted site at each growth stage. Sugar content was always lower at the polluted site in roots and stem but sizably higher in leaves, thus showing a failure of the process of photosynthate translocation. The sulphur level in roots, stem and leaves increased consistently. The leaf area was conspicuously reduced, leading to a significant loss in the total photosynthetic surface, despite an increase in the stem length and the number of leaves in the stressed ...

Coal-smoke emissions of a thermal power plant affected the physio-chemical status of Peristrophe bicalyculata (Reth) Nees, as observed at the pre-flowering, flowering and post-flowering stages of plant growth. The nitrate level was raised while nitrate reductase activity, and the soluble protein content of leaf declined heavily at the polluted site during different stages of plant growth, compared to the control. The rate of photosynthesis also decreased under the pollution stress. Sugar level in root, stem and leaves increased with growing age of the plant but was always lower at the polluted site than at the reference site. In roots, the difference was marginal till flowering stage and quite conspicuous afterwards; stems showed a reverse pattern of variation. Sulphur content was higher at the polluted site in all the organs and at each stage of the plant life. The Zn and Fe concentrations were reduced in all plant parts under the pollution stress. Copper content in root was consistently low at the polluted site. In the stem and leaves, however, it was almost equal on both the sites at the pre-flowering stage but showed a wide difference during the later part of plant ontogeny.

Study of the foliar responses ofPeristrophe bicalyculata (Reth) Nees to the pollution caused by thermal power plant emissions revealed that the stomatal size, pore length, density, and index, as well as the photosynthetic rate and total chlorophyll content were reduced inP. bicalyculata plants at the polluted site in pre-flowering, flowering as well as post-flowering stage of plant growth. Contrary to this, stomatal conductance increased at each stage. The intercellular level of carbon dioxide was raised in the pre-flowering and flowering stages but decreased later at the polluted site.