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

Abstract

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.

Foliar characteristics, cambial activity and wood formation in Azadirachta indica A. Juss. as affected by coal–smoke pollution

“…Mostly, NR activity was at its lowest in winter when nitrate content was normally high. Similar changes with NR activity and nitrate content have been observed in Peristrophe bicalyculata (Nighat et al, 2008). Inhibition of NR activity can stem from a reduced supply of NADH or NO 3 À to the site of enzyme synthesis and/or from the failure of detoxifying mechanisms to operate (Klump et al, 1989).…”

Behavioral responses of leaves and vascular cambium ofProsopis cineraria(L.) Druce to different regimes of coal-smoke pollution

“…Leaf NRA did not show any obvious correlation with leaf area and/or lamina mass per unit area in Camptotheca accuminata seedlings (Sun and Yan 2004). Whereas NR activity in P. cineraria declined with increasing degrees of pollution, the reverse was true for nitrate contents (Figure 3), thus conforming to the situation observed recently in Peristrophe bicalyculata (Nighat et al 2008) and Azadirachta indica (Iqbal et al 2010). NR activity was at its lowest during winter, when nitrate content was usually high.…”

“…In consequence of a reduced photosynthesis, concentration of reducing sugars in leaves of P. cineraria declined with growing pollution load, showing a minimum at the most-polluted site ( Figure 4), as was the case with P. bicalyculata (Nighat et al 2008) and A. indica (Iqbal et al 2010). The relatively high sugar content during the pre-monsoon or monsoon periods could possibly emanate from a breakdown of starch into simple sugars during these periods of active growth.…”

“…Chlorophyll a may be more sensitive to pollution effect than chlorophyll b in some species (Mandre and Tuulmets 1997), while the reverse may apply to others (Ali et al 2008;Nighat et al 2008;Iqbal et al 2009). Both the chlorophylls may also show a comparable sensitivity (Singh et al 1990).…”

“…The reduction in soluble protein content could be attributed to a breakdown of existing proteins and/or a reduced protein synthesis which may cause enrichment of amino acid pools (Williams and Banerjee 1995). Reduction of protein content could also be related to a decreased photosynthesis (Kramer and Kozlowski 1979;Nighat et al 2008).…”