Coal-smoke pollution modifies physio-chemical characteristics of tissues during the ontogeny of Peristrophe bicalyculata

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.