Abstract
Maize is an economic crop that is also a candidate for use in phytoremediation in low-to-moderately Cd-contaminated soils, because the plant can accumulate high concentration of Cd in parts that are nonedible to humans while accumulating only a low concentration of Cd in the fruit. Maize cultivars CT38 and HZ were planted in field soils contaminated with Cd and nitrilotriacetic acid (NTA) was used to enhance the phytoextractive effect of the maize. Different organs of the plant were analyzed to identify the Cd sinks in the maize. A distinction was made between leaf sheath tissue and leaf lamina tissue. Cd concentrations decreased in the tissues in the following order: sheath > root > lamina > stem > fruit. The addition of NTA increased the amount of Cd absorbed but left the relative distribution of the metal among the plant organs essentially unchanged. The Cd in the fruit of maize was below the Chinese government's permitted concentration in coarse cereals. Therefore, this study shows that it is possible to conduct maize phytoremediation of Cd-contaminated soil while, at the same time, harvesting a crop, for subsequent consumption.
Highlights
Heavy metal contamination of agricultural soils is a worldwide problem [1], and in China the problem is especially serious
If all of the low- or moderately-contaminated croplands were removed from agriculture production, it would be impossible to meet the Chinese people’s food needs
The aim of this study was to investigate the uptake and distribution of Cd in sweet maize enhanced by nitrilotriacetic acid (NTA) under the field condition
Summary
Heavy metal contamination of agricultural soils is a worldwide problem [1], and in China the problem is especially serious. Maize is a familiar agricultural crop that is widely adapted to regions of China and can be cultivated . It has greater dry-mass than many heavy metal hyperaccumulative plants, such as Thlaspi caerulescens and Arabidopsis halleri. The roots and straws of maize can accumulate many kinds of heavy metals, including Cd, from contaminated soil. The seeds and fruits from maize generally accumulate metals at lower concentrations than leaves or roots [1]. After harvesting seeds and/or fruits from the plants, the straw, and roots, with their load of toxic metals, can be removed from the contaminated soil. With each successive growth cycle, the contaminated soil becomes cleaner than before
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