ASSESSING AND ARRESTING TRANSFER OF ARSENIC FROM SOIL TO RICE PLANT
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Date
2019
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DIVISION OF SOIL SCIENCE AND AGRICULTURAL CHEMISTRY ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
The problem of arsenic (As) contamination in soil, water and food materials has been
increasing day by day and attracting the attention of researchers globally. The worst
affected areas probably include Bengal delta basin, where at least 36 million people
have been exposed to As hazard. Manifold enhancement in the level of As was also
reported in soil and water with subsequent transfer of As to human food chain, mainly
via drinking water and plant. Much progress has not been made so far to overcome the
problem of As-pollution caused by the consumption of edibles. Hence in the present
investigation entitled “Assessing and arresting transfer of arsenic from soil to rice
plant”, relative As uptake ability of rice cultivars, distribution of As in different plant
parts as affected by applied silicate and release of organic acids from rice roots as
affected by As were assessed in pot and solution culture experiments. For this
purpose, a pot experiment was conducted to assess the effect of applied silicate (@ 0,
250 and 500 mg kg-1
) on As uptake ability of four rice cultivars viz. IR-36, Khitish,
Satabdi and Badshabhog, using an As-polluted soil, collected from West Bengal.
Besides, a solution culture experiment was conducted to assess the organic acids
secreted by rice roots due to As application (@ 0 and 100 µg L-1
). Results indicated
that the relative ability to accumulate As in rice grain was minimum in case of
Badshabhog (0.06 mg kg-1
) as compared to Khitish (0.24 mg kg-1
), IR-36 (0.34 mg kg1
) and Satabdi (0.36 mg kg-1
). More or less, a similar trend of As accumulation in the
straw of different cultivars was obtained. Arsenic content in the rice husk ranged from
0.52 to 0.63 mg kg-1
and there was no significant variation across the cultivars. On an
average, translocation factors of As from shoot to husk were 0.47, 0.18, 0.17 and 0.11
for Badshabhog, IR-36, Satabdi and Khitish, respectively, with the corresponding
values for husk to brown rice were 0.09, 0.55, 0.71 and 0.39. Translocation factor of
As from root to shoot was recorded as 0.52 for IR-36, 0.42 for Satabdi, 0.35 for
Badshabhog and 0.31 for Khitish. On average, there was a significant reduction in As
content in brown rice to the tune of 14.3 and 28.6% where sodium metasilicate
(Na2SiO3) was added @ 250 and 500 mg kg-1
, respectively. The highest concentration
of total weak acid was secreted by IR-36 (0.82 mN), followed by Khitish (0.58 mN),
Satabdi (0.44 mN) and Badshabhog (0.36 mN), which, by and large, appeared to be
negatively related with As content in brown rice of the respective cultivars. However,
the concentration of all the organic acids (citric, malic and succinic acid) as quantified
in the solution culture was not varied with rice cultivars except lactic acid, which also,
in turn, did not have any definite trend in respect of As accumulation in rice cultivars.
Integrated use of low As accumulating rice cultivars and silicate can be a promising
and potential strategy to arrest the transfer of As from soil to the grain of rice, grown
in polluted soils.
Description
T-10179
Keywords
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