The Properties Of Genetic Ecology On Cadmium Accumulation In Rice (Oryza Sativa L.)

At present, a huge area of arable land in China has been contaminated by toxic heavy metals, which not only inhibits the growth and development of crops, leading to reduced yield and quality, but also poses a great threat to human health via food chain due to uptake by crops .It is, therefore, imperative to reduce toxic heavy metal concentrations in edible parts of crops, particularly in rice, which is one of the most frequently consumed cereals worldwide. The uptake, accumulation of and tolerance to some heavy metals vary greatly among plant species and among genotypes within a species. In rice, a significant difference also exists among genotypes in heavy metal concentrations in grains and their tolerance, thus providing a possibility of developing rice cultivars with high tolerance and low grain accumulation of toxic heavy metals.It is considered the most economic and efficient approach to reduce heavy metal concentrations in rice grains planted on the slightly or moderately contaminated soils. Meanwhile, heavy metal uptake and accumulation by crops is a function of the complex interaction of plant, soil, environmental and cultivated factors that affect bioavailability of heavy metals in soil. Up to date, however, the genotypic and environmental variation of toxic heavy metal concentrations in rice grains and its mechanism remain poorly understood ,thus hindering the progress of breeding and agronomic improvement in heavy metal tolerance and accumulation in grains, the present experiments were carried out to study the genotypic and environmental variation Cd concentrations of rice grains and to screen out some since genotypes with low Cd concentrations in grains, focusing on the most widespread and severe Cd in Southeast of China. Meanwhile, the approaches of identifying the rice genotype with distinct Cd-tolerance, and accumulation, and the effects of Cd on rice growth and nutrition metabolism were also studied. The main results are as follows:1 Studies on screening of rice (Oryza sativa L.) germplasm tolerant to Cd stress72 rice cultivals were screened with different Cd tolerance by adding Cd in the hydroponic culture nutrition. The results indicated that a significant genotypic variation of Cd tolerance in the tested 72 cultivars. A cluster analysis of tolerance indices, including shoot height and weight, root length and weight of the plants exposed to 0.2mg/L Cd level,...