不同水平Cd胁迫下低累积Cd水稻品种筛选

通过盆栽试验,研究了10个水稻品种在不同水平Cd胁迫下稻米对Cd的吸收累积情况。结果表明,水稻对Cd具有很强的吸收累积能力,但不同品种对Cd的吸收存在显著差异,相同条件下不同水稻品种稻米的Cd最高与最低含量差异值高达7.36 mg/kg;通过测定叶绿素相对含量（SPAD值）发现,随着添加的外源Cd浓度增加,水稻SPAD值呈现出先增加后减少的趋势,说明低浓度Cd可促使水稻生长,高浓度Cd则会抑制其生长;经聚类分析筛选出1个低累积Cd水稻品种——F优498,其稻米Cd含量仅为0.15 mg/kg（不添加外源Cd条件下）,低于国家食品卫生安全标准规定的限定值（0.20 mg/kg）。相关性研究发现,水稻普遍对土壤Cd有良好的吸收作用,稻米会随着土壤Cd含量的增加大量累积Cd,因此,筛选得到的Cd低累积水稻品种也只适合栽种于无污染或Cd轻度污染区域。

Screening of Rice Varieties with Low Accumulated Cd under Different Levels of Cd Stress

The absorption and accumulation of Cd in 10 rice varieties were studied by pot experiments under different levels of Cd stress. The results showed that rice has a strong ability of absorbing and accumulating Cd, but there were significant differences in the absorption level in different rice varieties. The difference in Cd content of different rice varieties under the same conditions is as high as 7.36 mg/kg. By measuring the relative content（SPAD）of chlorophyll, it was found that with the increase of the content of exogenous Cd, the SPAD value of rice showed a trend of first increasing and then decreasing. It indicated the low content of Cd promote the growth of rice, while high content of Cd inhibit its growth. A low-accumulation Cd rice variety, F You 498, was selected by cluster analysis. Its Cd content in grain was only 0.15 mg/kg（without adding exogenous Cd）, which was lower than the limit value stipulated by the national food safety standards（0.20 mg/kg）. Correlation study found that rice had a good absorption effect of Cd in soil generally, and rice will accumulate lots of Cd with the increase of Cd content in soil. Therefore the selected low Cd accumulation rice variety were only suitable for planting in non-pollution or lightly Cd pollution areas.