晚粳稻籽粒中As、Cd、Cr、Ni、Pb等重金属含量的基因型与环境效应及其稳定性

Genotypic and Environmental Variation and Their Stability of As,Cr,Cd,Ni and Pb Concentrations in the Grains of Japonica Rice

选择籽粒Cd、Cr、As、Ni和Pb等重金属含量差异较大的12个晚粳稻基因型,种植于浙江省晚粳稻主产区嘉兴、湖州、杭州、宁波、绍兴市的6个试点,研究籽粒中5种重金属含量的基因型与环境变异及其稳定性、籽粒和土壤有效态(DTPA提取态)Cd、Cr、As、Ni和Pb等重金属含量之间及与Fe、Zn含量之间的关系,以及土壤pH对籽粒重金属积累的影响。结果表明,环境、基因型及其互作效应对籽粒重金属含量的效应均达极显著水平,表明筛选和选育籽粒重金属含量低的品种以及通过农艺措施减少籽粒重金属含量是可能的。同时,籽粒中这5种重金属含量的稳定性因环境、基因型而有较大差异,且亦因重金属种类而异。因此,为降低籽粒重金属含量,应针对特定重金属污染的环境进行基因型选择,并同时考虑基因型籽粒重金属含量的稳定性。土壤pH不仅影响土壤重金属有效性及水稻籽粒中重金属积累量,还影响籽粒重金属积累的基因型与环境互作效应(即积累稳定性)。此外,土壤中一些重金属常发生复合污染,如Cd和Cr、As或Ni,Cr和As,Pb和As间表现为协同消长,Cd含量较高的稻米往往As和Pb含量也高,Cr和Ni含量以及As和Pb含量之间也呈正相关。

Contamination of toxic heavy metals in soil not only causes the reduction of crop yield, but also poses a potential threat to human health due to their uptake and accumulation in edible parts of crops. The heavy metals accumulation in rice grain varies with genotypic, environmental and their interaction. However, little is known about genotypic and environmental effect on the toxic heavy metal accumulation in rice grain. In this study, the genotypic and environmental variations of Cd, Cr, As, Ni and Pb concentrations in rice grains, and the relationships between these heavy metals and Fe, and Zn were investigated by using twelve japonica rice genotypes, planted at six locations in five cities （Jiaxing, Huzhou, Hangzhou, Shaoxing and Ningbo） of Zhejiang Province, China （Table 1）. The results showed that genotypic and environmental effects, and their interaction were all highly significant on these five heavy metal concentrations in rice grains （Table 2 and Table 3）. It was suggested that the concentration of these heavy metals in grains of rice could be reduced through genetic and agronomic improvement. Meanwhile, the stabilization coefficient of these heavy metal concentrations in rice grains varied with environment, genotype as well as individual metal element, indicating the importance of rice cuhivar based on environmental conditions. In addition, soil pH affected not only soil heavy metal availability and grain heavy metal concentrations, but also the stability （interaction of genotype by environment） in grain heavy metal accumulation （Table 4）. Correlation analysis indicated Cd and Cr, As or Ni, As and Cr, and Pb and As levels in soil, and Cd and As or Pb, Cr and Ni, and As and Pb concentrations in rice grains were closely correlated （ Table 5）. More investigation should be done to determine the relationships between mineral nutrients and toxic heavy metals in their availability in soil and accumulation in rice for developing the rice cuhivars with a desirable concentration of nutrient elements and lower concentration of the toxic heavy metals.