A Predictive Model for the Accumulation of Cadmium by Container-Grown Plants1
- C. L. Browne,
- Y.-M. Wong and
- D. R. Buhler2
Research into the dietary availability of Cd, a toxic heavy metal, called for prediction of Cd accumulation by edible crop species to be grown to maturity under greenhouse conditions. Examination of the literature revealed that Cd accumulation in plants grown under greenhouse and oxic conditions could be generally described, with high correlation, by the equation: log P = α + β log CdDTPA, where P is plant Cd (µg Cd/g dry wt), CdDTPA is the DTPA (diethylenetriaminepentaacetic acid) extract estimate of available soil Cd (µg Cd/g soil), and α and β are linear regression coefficients. Published data were fitted to the above equation to determine whether the model coefficients exhibited consistent relationships that would predictably account for the potential effect of soil type, species, and experimental conditions on the accumulation of Cd by plants. For a given experimental situation, β was found to be principally a function of soil pH and cation exchange capacity (CEC), and a single mean value was deemed appropriate for all species. The coefficient α was mainly a characteristic of plant species, and the relative magnitude of the difference among species in the value of α tended to remain constant for differing experimental conditions. Assuming that such a relationship was common to greenhouse crops, estimates of α for several species to be grown under our conditions were derived from the literature. This was accomplished by comparison with values of µ for test crops of spinach (Spinacia oleracea L.) and lettuce (Lactuca sativa L.) grown under our conditions. Substitution of estimated values of α and β into the above equation permitted the successful prediction of soil Cd additions (0.5–15 µg Cd/g) necessary to achieve a specified level Cd in the range of crop species subsequently grown to maturity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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