| Rice Cd pollution has become the focus of attention.The studies showed that Cd content in brown rice was significantly correlated with rice variety.Therefore,it is important to understand Cd accumulation characteristic in different genotype cultivars.In this paper we screened and identified Cd accumulation genotypes of rice and select 3 cultivars with different genotypes for further analysis.The main results are as follows: 1?First year,we evaluated genotypes by Cd content in brown rice,and obtained 5 cultivars with low-Cd and 6 cultivars with high-Cd from 100 cultivars.Next year,we analyzed Cd content of different organs of the 11 cultivars and classified the genotypes,among which,Xianwanxian12 is low-Cd type in both brown rice and culm,Weiyou 46 is high-Cd type in both brown rice and culm,and KT27 S is low-Cd in brown rice but high-Cd in culm type.We took Xianwanxian12,Weiyou46 and KT27 S for further analysis.2?Analysis of Cd accumulation characteristic on Xianwanxian12 and Weiyou46 during grouting to mature stages were performed.The results showed that Cd content and Cd accumulation of individual tillering line gradually increased after the grouting.The Cd accumulation of Weiyou46 was higher than that of Xiangwanxian12.The total Cd accumulation of Weiyou46 was 158.8% more than Xiangwanxian12 atmature stage,Weiyou46 has stronger Cd accumulation ability than Xiangwanxian12.The proportion of the Cd in root part of Xiangwanxian12(26.7%)was higher than that of Weiyou46(18.6%),but the shoot part was opposite.The proportion of the Cd in brown rice,chaff,spike,flag leaf,culm of Weiyou46 is higher than Xiangwanxian12,while the proportion of the Cd in other leaves of weiyou46 was lower than Xiangwanxian12,indicating that Weiyou46 has stronger ability to transport Cd from root to shoot than Xiangwanxian12.3?Cd content in various organs of rice and Cd accumulation per plant was positively correlated with Cd content of soil.Xiangwanxian12 did not exceed Cd content safty standard in brown rice when planted in all three Cd-containing soils(0.28?0.6?1.0 mg/kg).Weiyou46 collected from 0.28 mg/kg of Cd soil did not exceed Cd content safty standard in brown rice as well,but exceeded Cd standard when planted in other two Cd concentration soils,indicating Weiyou46 is more easily influenced by Cd in the soil.4?Cd accumulation was negatively correlated with soil pH(4.5,5.5,6.5).Cd content in brown rice of Xiangwanxian12 exceeded the standard when grown under pH 4.5 soil condition,however it did not exceed in soil pH 5.5?6.5.Although Cd content of Weiyou46 in brown rice exceeded under 3 experiment soil pH condition,the Cd content in brown rice under soil pH 6.5 condition was 81% lower than that under pH 4.5 soil.5?The effect of wet irrigation on Cd accumulation of KT27 S was performed.The results showed that in mature period,KT27 S accumulated much higher Cd when treated with wet irrigation than kept in flooding irrigation,and Cd accumulation increased as the wet irrigation duration prolonged(5 d,8 d,11 d).Under wet irrigation condition,Cd content in brown rice increased gradually,from 0.19 mg/kg to 0.21 mg/kg by 5 d,to 0.38 mg/kg by 11 d.However Cd content in other organs increased rapidly by 5 d.As KT27 S diaplayed low Cd trait in brown rice and high Cd trait in vegetative organs,it can be a potential dual purpose rice resouce applied in both rice production and soil bioremediation... |
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