Genotypic variation in grain cadmium concentration of lowland rice

Abstract

Cadmium (Cd) contamination of paddy rice soils is commonly observed in the Yangtse River Delta, China. Large Cd uptake by rice plants and its translocation into the grains can entail human‐health risks. Genotypic variations in Cd uptake and a differential Cd partitioning into grains will be the basis for developing a rice screening or breeding tool for low grain Cd. A field experiment, conducted at the experimental farm of Jiaxing, Zhejiang province from 2002 to 2004, compared 38 rice genotypes of different types (indica vs. japonica) collected from the Yangtse River Delta. The results showed large differences in Cd concentrations in straw, brown rice, and grain chaff among the rice genotypes grown on Cd‐contaminated soil. Concentrations in brown rice ranged from 0.06 to 0.99 mg Cd kg–1. The total Cd uptake in brown rice varied between 0.96 and 28.58 μg plant–1. In general, indica‐type cultivars accumulated significantly more Cd than the japonica‐type cultivars. The Cd concentration in straw was highly correlated with that in brown rice. While significant differences in the Cd‐partitioning ratio (% share of total Cd uptake found in brown rice) among rice genotypes were observed, these were not correlated with Cd concentration of brown rice. This indicates that the Cd accumulation in rice grains appears to be governed mainly by the Cd uptake by the plant and probably not by differential Cd partitioning. The large genotypic variation suggests the possibility to lower the Cd content of rice by genotype selection. The development of such breeding tools should focus on low Cd uptake rather than Cd partitioning between straw and grain.

Cadmium Uptake and Distribution in Fragrant Rice Genotypes and Related Consequences on Yield and Grain Quality Traits

“…These differences in Cd concentrations may arise from the variation of Cd uptake and translocation ability of cultivar type. In similar studies, marked positive Journal of Chemistry correlations in Cd concentrations were reported between the rice roots, stems leaves, and grains [17], and marked linear correlations between Cd concentrations in rice grains and straws/roots Cd concentrations ( < 0.01) were also shown [18,19]. The results in our study further illustrated variations in Cd uptake and translocation among the five cultivars as well as organs of the same cultivar.…”

Characterization of soil heavy metal pools in paddy fields in Taiwan: chemical extraction and solid-solution partitioning

“…The range in SOM, clay, and CEC within each field is limited as is indicated by the low standard deviation (Table 1). Ranges in soil properties measured here are comparable to those measured by others in rice paddy fields (He et al 2006;Simmons et al 2008) 3.2 Total metal content Total metal levels vary considerably between and within fields, and they range from background levels to levels beyond current soil quality standards used in Taiwan (EPA 2006; Table 2). For the metals studied here, the number of soil samples with total metal contents in excess of the present soil monitoring values for cropped soils increases from 2.9% for Cr, 6.3% for Zn, 10.1% for Ni, 13.0% for Pb, 13.3% for Cu to 26.7% for Cd.…”

Subcellular Distribution of Cadmium in Two Paddy Rice Varieties with Different Cooking Methods

“…This was not in agreement with the observations of many researchers that have shown a 1.5 to 3.0 times higher Cd concentration accumulating in the grains of the Indica variety compared with the Japonica variety [32] [33], which is related to the oxidizing and translocation capacity of the roots [12] [34]. Although more Cd accumulated in the roots and shoots of the Japonica variety, the accumulated Cd would not be easily transferred to the grains.…”