Abstract:

To provide a scientific basis for prevention and control measures of reducing cadmium accumulation in rice, two kinds of soils, lightly and heavily contaminated by cadmium, were selected for cultivating two rice varieties, low-cadmium-absorption variety (‘Xiushui 519’) and high-cadmium-absorption variety (‘Zheyou 18’) by pot experiment, respectively. The whole rice plant was collected at different growth stages, and the dry matter accumulation and the cadmium content were analyzed. The results showed that the cadmium contents in all organs of ‘Zheyou 18’ were significantly higher than those of ‘Xiushui 519’, and the order of cadmium accumulation was: root > stem > leaf > grain. The proportion of root cadmium accumulation in the whole plant was more than 50% at all growth stages, and was higher in early stage than that in late stage. The proportion of stem cadmium accumulation in the whole plant was higher in heavily polluted soils than that of the lightly polluted soils, and higher in rice plant with high cadmium uptake capacity than in that with low cadmium uptake capacity. In lightly polluted soils, the uptake of cadmium by rice mainly occurred at tillering and booting stage, and the cadmium content in the various organs decreased with rice growth at the later stage. In heavily polluted soils, rice absorbed cadmium strongly from tillering stage to milking stage, and cadmium accumulation in most of the organs increased with growth. In general, the growth period from tillering stage to filling stage is an important period to control cadmium uptake in rice, and that from filling stage to yellow maturity stage is the key period to control cadmium transfer from stem, leaf to grain in rice.

Key words: Rice Varieties, Growth Period, Uptake and Distribution, Cadmium Pollution, Soil, Control Technology