Effect of Chromium (VI) on Growth and Physiolgy of Giant Duckweed Spirodela polyrrhiza (L.) Schleiden

Abstract

Chromium is used in a number of industrial processes such as chrome plating, leather processing, textile manufacturing and steel production. From these and other anthropogenic sources, chromium enters the aquatic environment and thus becomes a contaminant of river water (NRCCBEAP, 1974), lakes and swamps (NRCCBEAP, 1974; Rogers et al., 1978; Young et al., 1982), ponds (Chandra et al., 1993) and irrigation waters in India (Kasim et al., 1989). In the natural environment, Cr-VI and Cr-III are stable oxidation states. Cr-VI is readily extractable from soils and considered to be most toxic form (McGrath & Smith, 1990). Although both Cr-III and Cr-VI are not essential for plants, significant amounts of Cr-VI are accumulated by plants like Lemna (Baszynski et al., 1981; Clarks et al., 1981), Ceratophyllum demersum (Garg & Chandra, 1990), Hydrilla verticillata (Sinha et al., 1993b) duck weed and other aquatic plants (Chandra et al., 1993). Giant duckweed Spirodela have been found to accumulate both Cr-VI (Staves & Knaus, 1985) and Cr-III (Tripathi & Chandra, 1991). The toxic effect of Cr-VI on growth and development of plants has been widely reported (Huffman & Allaway, 1973; Mangi et al., 1978; Smith et al., 1989; McGrath & Smith, 1990). Pillard et al. (1987) examined the inhibitory effect of Cr on photosynthesis.