Growing Rice Grain With Controlled Cadmium Concentrations

Abstract

Two solution studies were conducted a) to investigate the uptake of zinc (Zn) and cadmium (Cd) by rice plants (Oryza sativa L.) and interaction between these elements, and b) to determine experimental conditions for growing rice grain with desired Cd concentration for an animal feeding study. In both studies, free metal activities of cadmium and cationic microelements were buffered by an excess of chelating agents. The first study was a factorial design with two Zn levels (1.0 and 3.89 mM) and four Cd levels (0.81, 1.44, 2.56 and 4.55 mM) in the solution. In the second study, rice was grown in two solutions of different microand macro-element compositions and three Cd levels (0.0, 0.5, and 2.0 mM). In the first study, solution Zn concentration of 3.89 mM and corresponding free metal activity (pZn 2þ ) of 6.00 was toxic to young rice plants. With time, Zn concentrations in rice plants decreased while Cd concentrations increased. Toxic concentration of Cd in roots (about 100 mg kg À1 ) associated with

How Does Contamination of Rice Soils with Cd and Zn Cause High Incidence of Human Cd Disease in Subsistence Rice Farmers

“…Green and Chaney (unpublished) showed that with Cd activity which gives rice Cd levels found in the field, increased Zn activity had little effect on Cd uptake, confirming the field observations that Zn does not inhibit Cd accumulation by rice. On the other hand, the "Chino" solution supplied more Mn and gave significantly lower Cd accumulation in rice shoots and grain than the "Grusak" solution both with the same buffered Cd 2+ and Zn 2 activity [64] ( Table 1). …”

Tracing Cadmium from Culture to Spikelet: Noninvasive Imaging and Quantitative Characterization of Absorption, Transport, and Accumulation of Cadmium in an Intact Rice Plant

“…The mechanism of these phenomena could be explained as other heavy metals in the culture solution affecting the Cd absorption. Kukier and Chaney (2002) reported that different compositions of hydroponic culture solution with the same Cd concentration can lead to different Cd levels in rice grains. In our experiment, the heavy metal composition of the culture solution may have changed with time during the PETIS experiment, because fresh solution containing heavy metals was added to maintain the total volume.…”

Influence of external zinc and phosphorus supply on Cd uptake by rice (Oryza sativa L.) seedlings with root surface iron plaque

“…Recently Hassan et al (2005) showed that at high Cd supply (5 μmol l −1 Cd compared to 1 μmol l −1 Cd or without Cd), Zn (1.0 μmol l −1 ) significantly increased shoot Cd concentrations but reduced root Cd concentrations. Kukier and Chaney (2002) found that at high external Cd levels (2.56 and 4.55 μmol l −1 Cd), Zn (3.89 μmol l −1 ) significantly stimulated Cd translocation from roots to shoots in rice plants at later growth stages.…”

“…The chemical similarity of Cd and Zn leads to the co-existence of the two elements, and both antagonistic and synergistic interactions in plant uptake have been reported in hydroponic and field experiments (Hart et al 2005;Kukier and Chaney 2002). P fertilizers are regarded as an important source of Cd pollution in cultivated soils, and Cd and P may have synergistic interactions (Lagriffoul et al 1998;Moral et al 1994).…”