不同基因型水稻糙米对镉、铅的吸收特性

Absorption and Accumulation of Cd and Pb in Brown Rice of Different Genotypes

【目的】筛选出低吸收累积重金属Cd、Pb的水稻种质资源,为Cd、Pb污染地区水稻种植品种的选择和抗性品种的选育提供理论依据。【方法】选用60个水稻品种,用塑料盆置于网室水泥槽中种植水稻,共分3个组,第1组为不加重金属的对照组;第2组为添加重金属Cd的Cd处理组,以CdCl2·2.5H2O形态加入土壤中,使Cd含量达到土壤环境质量标准三级中镉的临界值(1mg·kg^-1);第3组为添加重金属Pb的Pb处理组,以Pb(CH3COO)2·3H2O形态加入土壤中,使Pb含量达到土壤环境质量标准三级中铅的临界值(500mg·kg^-1)。成熟期收获种子晒干,保存3个月后,采用电感耦合等离子体质谱法(ICP-MS)测定3组材料糙米中Cd和Pb含量。【结果】(1)不同水稻品种对Cd的吸收力差异显著,Cd处理组糙米Cd含量变幅在0.133~3.308mg·kg^-1,对照组糙米Cd含量变幅在0.005~0.224mg·kg-1,Cd处理组糙米Cd平均含量是对照组的19.63倍,差异达极显著水平(P<0.01),且不同品种Cd处理组糙米Cd含量与对照组糙米Cd含量呈极显著正相关;Cd处理组有1个品种(台粳8号)糙米Cd含量在可食用标准0.2mg·kg^-1以内,说明台粳8号是低吸收Cd的品种。(2)不同水稻品种对Pb的吸收力差异显著,Pb处理组糙米Pb含量变幅在0.183~2.123mg·kg^-1,对照组糙米Pb含量变幅在0.010~0.288mg·kg^-1,Pb处理组糙米Pb平均含量是对照组的10.66倍,差异达极显著水平(P<0.01),但不同水稻品种Pb处理组糙米Pb含量与对照组糙米Pb含量相关不显著;Pb处理组有2个品种(金早6号、宁粳216)糙米Pb含量在可食用标准0.2mg·kg^-1以内,说明金早6号、宁粳216是低吸收Pb的品种。(3)籼稻糙米Cd含量显著高于粳稻,但Pb含量籼稻与粳稻无显著差异。(4)不同种皮色水稻品种对Cd、Pb吸收力有差异,表现为红米>黑米>白米。【结论】土壤环境三级质量标准的稻田已基本不适宜种植水稻,但水稻对Cd、Pb的吸收力存在明显的基因型差异。从众多种质材料中可以筛选出适宜在轻度Cd、Pb污染地区种植的水稻品种,并可为培育抗重金属污染水稻新品种提供重要的种质材料。

【Objective】 Rice germplasms that are low in absorbing and accumulating Cd and Pb were selected for breeding resistant varieties.【Method】 In a netted chamber, 60 genotypes of rice were planted in plastic pots in cement tanks and divided into 3 groups.Group I was free of added heavy metals to be used as control;Group II contained CdCl2 ·2.5H2 O to simulate the 3 rd grade quality of soil contaminated with Cd1 mg·kg^-1;and, Group Ⅲ of the same grade soil with Pb 500 mg·kg^-1 by the addition of Pb(CH 3 COO)2 ·3H2 O.Rice grains were harvested at maturity, dried, and stored for 3 months prior to Cd and Pb determinations in the unpolished rice samples using the inductively coupled plasma mass spectrometry (ICP-MS).【Result】(1) Significant variations in Cd absorption were found among the genotypes.Group I had a Cd content ranging from 0.005 to 0.224 mg·kg^-1 , as compare to Group II of 0.133-3.308 mg·kg^-1 , showing an average of19.63-fold difference significant at P <0.01.Among the varieties of rice, a significant correlation existed between the Cd contents of control and treatment at P <0.01.The Cd-tolerant Taijing 8 only sustained a level below the acceptable threshold of Cd 0.2 mg·kg^-1 for safe consumption.(2) The Pb absorption by the rice varied significantly as well. Group I had Pb 0.010-0.288 mg·kg^-1 , while Group III Pb 0.183- 2.123 mg·kg^-1 , showing an average of10.66-fold significant difference ( P <0.01).However, there was not an apparent correlation between the Pb contents of control and treatment. Jinzao 6 and Ningjing216 exhibited in the trial a Pb tolerance with a sustained content below the 0.2 mg·kg^-1 standard.(3) The accumulated Cd in Indica rice was significantly higher than that in Japonica , but not on Pb.(4) Based on color of the hull, the Cd and Pb absorption by red rice seemed to be the highest, followed by black, and the lowest white.【Conclusion】 Basically, any soil below 3 rd grade on the environmental quality is not recommended for rice planting.Since there were significant differences among rice genotypes on their tolerance to Cd and Pb contamination, a selection guideline was made available for breeding varieties that could be cultivated on lands moderately contaminated by Cd and Pb.