Rana P.
Singh
(Corresponding author)
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Department of Environmental Sciences, B.B.A.
University, Lucknow
- 226 025, India
e-mail: ranapsingh1@hotmail.com
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Publication Data
Paper received:
01 January 2010
Revised
received:
10 June 2010
Accepted:
30 July 2010
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Abstract
Cadmium application
inhibited various growth and biochemical parameters in seedlings of five
cultivars of Brassica juncia
L. with different magnitude at lower Cd supply,
however, at higher metal applications the variation in Cd
toxicity ranged with minor differences. The seedling vigour
index (SVI) was inhibited more severely in Gangotri
(62.25% over control) and least in Pusa Jai Kisan
(8.95%) at 1.0 mM CdCl2.
The SVI of all five mustard cultivars, however, severely inhibited
(84.29-91.80%) at 5.0 mM Cd.
The root and shoot elongation in 7 days old seedlings were inhibited by
32.39-40.38 and 11.83-56.40% respectively at 1.0 mM
CdCl2, whereas the varietal
differences in root and shoot elongation were 76.71-82.47 and 71.57-78.91
respectively at 5.0 mM CdCl2.
The genotypic differences at lower Cd level
were more pronounced in shoot elongation than that in the root elongation.
The dry weight and moisture content of the seedlings, however, does not show
much varietal differences even at lower Cd level, though the Cd
toxicity increased at higher level of Cd
application. The metal tolerance index (MTI) and % phytotoxicity
of 3 days old seedlings ranged between 43.30-98.37 and 1.63-56.70%
respectively at 1.0 mM CdCl2
for different mustard genotypes, whereas at 5.0 mM CdCl2 these factors ranged between 12.26-20.92
and 80.08-87.74% respectively. The varietal
differences of MTI and % phytotoxicity was,
however, less pronounced at all the metal levels when the seedling attained
an age of 7 days. A similar trend of genotypic variation was noticed in Cd accumulation in the seedlings at lower and higher
levels of Cd supply to the seedlings. Amongst some
biochemical parameters e.g. photosynthetic pigments, carbohydrates and
proteins in the leaves, the photosynthetic pigments i.e. chlorophylls
and carotenoids were decreased more drastically.
The carbohydrate content of leaves, however, was the least affected
component. Our data indicate that the differential toxicity of cadmium to
Indian mustard genotypes was dependent on the level of contamination and
growth phases.???????
Key
words
Brassica, Germination, Cadmium toxicity, Metal tolerance index, Seedling
vigour index
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