Screening of low-bioaccumulation rice varieties in cadmium contaminated paddy fields with high geological background

【Objective】A plot study was performed to explore the bioaccumulation and transport of cadmium(Cd) in the paddy fields of a high geological-background area, and to screen low-bioaccumulation rice varieties, providing reference for safe rice production in the area.【Method】Ten rice varieties that spread throughout central Kaiyang of Guizhou were tested by plot experiment. The Cd content of different soil and rice tissues was determined, and the enrichment and transport characteristics of Cd were compared with different rice varieties, and combined with rice yield and cluster analysis to select Cd low accumulation rice varieties.【Result】The soil pH of the tested rice varieties was 5.88 to 6.37, full Cd content was 0.89 to 1.30 mg/kg, and effective Cd content was 0.40-0.58 mg/kg. There was no significant difference in soil pH and Cd content between different varieties(P>0.05, the same below). Cd content in different tissues of rice was high in stem and root. Compared with rhizosphere soil, Cd was obviously enriched in rice stems and roots, and the enrichment coefficient was more than 1.00, but the enrichment coefficient of most varieties of husk and brown rice was less than 1.00. The Cd transport coefficient was high in brown rice/chaff and stem/root transport coefficient, and the capacity of Cd transport from root to stem and chaff to brown rice was relatively strong, close to or over 1.00. On the premise of no significant difference in yield among rice varieties, combined with cluster analysis, 10 rice varieties could be divided into three categories:category Ⅰ(lower value category) including Chengyou 1479 and Tianyou 1177;category II(intermediate value category) including C Liang U Huazhan, Heinuo 80, Chuanhuayou 320, Hongyou 2, C Liang U Huazhan and Luxianyou 110;category Ⅲ(higher value category) including Jinyou 2017 and Yixiangyou 2115.【Conclusion】Among the 10 tested rice varieties, all parts of local main rice varieties are relatively easy to enrich Cd. Among them, the Cd content of Jinyou 2017 and Yixiangyou 2115 brown rice seriously exceeds the standard, so it is not recommended to plant in Cd polluted rice fields. The brown rice of Chengyou 1479 and Tianyou 1177 has low Cd content, which can be populari-zed as rice varieties with low Cd accumulation.