Abstract: 【Objective】 It is important to minimize the influx of cadmium (Cd) to the human food chain through consumption of agricultural products. The characteristics of the uptake and distribution of Cd in pollution-safe materials were studied to provide Cd safety rice germplasm resources. 【Method】 A field experiment was conducted to investigate the differences of 56 rice parent materials in Cd uptake and distribution in polluted paddy field. According to cluster analysis, the pollution-safe materials were chosen by the Cd content of the brown rice, and Cd uptake and distribution characteristics of rice parent materials were analyzed.【Result】There were significant differences in the Cd contents and Cd accumulations at tillering stage(CV=44.05% and CV=50.21%), booting stage(CV=23.57% and CV=28.62%) and mature stage(CV=44.98% and CV=44.69%) among the 56 rice parent materials when the field soil Cd content was 13.89 mg·kg^-1. Meanwhile, the Cd contents in brown rice ranged from 0.15 to 1.77 mg·kg^-1 among the parent materials, the ratio of maximum and minimum value reached 11.80, and the minimum value of Cd content was lower than the National Food Safety Standard. The 56 rice parent materials were divided into pollution-safe materials, general materials and high accumulation materials depending on the Cd content of brown rice. The Cd content of brown rice of pollution-safe materials was 0.2 mg·kg^-1 which was significantly lower than that of the general materials (0.65 mg·kg^-1) and the high accumulation materials (1.57 mg·kg^-1). Moreover, the lowest Cd contents of chaff and grain partition coefficient were also observed in pollution-safe materials. Shoot Cd contents in the three kinds of materials were significantly decreased with the growth stage prolonged. Furthermore, shoot Cd contents in the pollution-safe materials were significantly lower than that of the general materials and high accumulation materials at tillering, booting and mature stages. Especially, the Cd contents in shoot of the general materials and high accumulation materials were 1.35 and 3.39 times higher than the pollution-safe materials at mature stage. The pollution-safe materials exhibited significantly lower Cd accumulations in shoots compared to the general materials and high accumulation materials at the three growth stages. The maximum differences among the three kinds of materials were observed at maturity stage. The Cd accumulations in shoots of the general materials and high accumulation of materials were 2.23 and 3.86 times higher than that of the pollution-safe materials at mature stage. The maximum differences among the three kinds of materials were also observed at maturity stage. The greatest Cd accumulation in shoots of pollution-safe materials was observed at sowing-tillering stage. However, there were no difference among the three growth stages in the general materials and high accumulation materials. Due to the lower metastatic ability of Cd to grain, the pollution-safe materials have lower Cd content in grain. Meanwhile, the distribution ratio of Cd accumulations in grain was 8.11% of the total Cd accumulations in aboveground of the pollution-safe materials, which was lower than that of the general materials (11.60%) and high accumulation materials (17.59%).【Conclusion】Among the pollution-safe materials, the Cd contents in the brown rice of D62B, IRBN95-90 and GRlu 17/ai TTP//lu 17_2 were lower than the National Food Safety Standard (0.2 mg·kg^-1). Thus, D62B, IRBN95-90 and GRlu 17/ai TTP//lu 17_2 can be considered as Cd safety rice germplasm resources for Cd-polluted farmlands.

Key words: rice, Cd pollution-safe materials, brown rice, partition coefficient