BEHAVIOUR OF CADMIUM IN SOIL AND ITS ABSORPTION BY PLANTS
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Date
2001
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AAU, Anand
Abstract
Cadmium is emerging as an important pollutant in the field of agriculture particularly in industrial state like Gujarat. The present research was undertaken to study (i) some important factors influencing the Cd availability in soil through an incubation study and (ii) uptake of Cd in a pot culture study. An incubation study consisted of five levels of Cd (0, 2.5, 5.0, 10.0 and 20.0 ppm) in presence of three levels each of P (0, 50 and 100 kg ha-1), FYM (0, 10 and 201 ha-1) and CaCOa (0, 5 and 10%) in three separate series for three incubation periods (30, 60 and 90 days). The pot culture experiment was conducted during Kharif, 1999 by growing chickpea upto flowering and wheat upto maturity stage in a clay and a loamy sand soils of Karvan and Anand with five levels of Cd (0, 2.5, 5.0, 10.0 and 20.0 ppm). The results of incubation study indicated that the availability of Cd increased with increasing levels of its application and the per cent fixation of applied Cd ranged between 25.2 and 14.3 with Cdo and Cd4 Ievels(20 ppm). The availability of Cd was found to decrease with application of increasing rates of P, FYM and CaCOa. Amongst these three, FYM @ 20 t ha-1 most effectively reduced Cd availability. The pot culture study indicated that a significant reduction in the dry weight of whole-plant and plant components of both the crops right from the lower level of Cd application (2.5 ppm). Wheat plant did not show any visual toxic symptoms, whereas chickpea plants showed visual symptoms for Cd toxicity at elevated Cd level. The content and uptake of Cd by plant components were significantly increased with Cd application. Amongst the different plant parts, the order followed for Cd content was: roots > stem > leaves > grain and for Cd uptake it was: stem> leaves > roots > grain. A restricted translocation of Cd from roots to above ground plant parts was noted. The N, Ca, Mg and S content did not differ significantly due to Cd addition but the antagonistic effect of Cd on P, K, Zn and Fe content in plant components was observed. Even after the crop harvest, about 22 to 27 per cent of the total applied Cd remained in available form, indicating possible residual effect also. Particularly, at Cd4 level, it crossed the critical level of 3.0 mg kg-1 suggested for Cd.
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Keywords
Agricultural Chemistry and Soil Science, A Study