| The plants have great enrichment coefficient of Cadmium(Cd). When Cd concent of plant is more than limition,it will affect not only crop yield and quality, but also people’s health. The agricultural products of Cd pollution caused widly public concern. A pot experiment with four levels of Cd additions (0,2,4 and 8 mg/kg soil) was conducted, each of the Cd concentration consisted 3 Se levels (0,0.07 and 0.14 mg/kg soil). Se, Cd contents were determined in different plant organs (leaves, stems, sheaths, roots)and different parts of grain(rice husk, rice bran, brown rice, polished rice), accumulation and distribution ratio in rice organs were calculated. Studied the effects of Se application on Cd and Se content and accumulation and distribution, absorption of other nutrient elements in rice organs and content of Cd in rice grain to explore countermeasures for rice planting on Cd polluted soils. The experimental results are as follow:1. Sequence of Cd content in rice organs was roots> stems> sheaths> leaves. Sequence of Cd content in grain was rice husk> rice bran> brow rice>polished rice. When added Cd concentration in soil was from 0 to 4 mg/kg, Cd content in different organs of rice, brown rice and polished rice increased significantly with the increase of Cd concentration. When added Cd concentration was higher than 4 mg/kg, Cd content increases in brown rice and polished rice were not significant. The Cd contents in brown rice were 0.221 mg/kg and 0.234 mg/kg under Cd2 (4 mg/kg) and Cd3 (8 mg/kg) treatments without Se application, which were 15.8 and 16.7 times higher than that of CdO, far more than the national food safety standards of China for Cd content (0.2 mg/kg). Cd content in different organs of rice and grain decreased significantly with the increase of Se concentration under same Cd concentration. Under the concentrations of Cdl, Cd2 and Cd3, Cd content of brow rice and polished rice with Se2 treatment were decreased by 21.64% and 27.08%,22.65% and 31.50%,22.29% and 16.09% compared to SeO, respectively. Cd accumulation in different organs of rice and grain decreased significantly with the increase of Se concentration under same Cd concentration. Under the concentrations of Cd1, Cd2 and Cd3, Cd accumulation of polished rice with Se2 treatment were decreased by 27.32%,18.01%(P<0.01), 6.91% and 16.09% compared to SeO. With the increase of Se concentration, when added Cd concentration was higher than 4 mg/kg, Cd distribution portion in roots was enhanced. Meanwhile, Cd distribution portion in plants decreased. When added Cd concentration was 2 mg/kg, Cd distribution portion in rice husk got higher with the increase of Se concentration, meanwhile, Cd distribution portion in polished rice decreased as Se concentration raised.2. Sequence of Se content in rice organs was roots> leaves> stems> sheaths. Sequence of Se content in grain was rice bran> rice husk> brow rice>polished rice. Se content and Se accumulation in different organs of rice and grain decreased significantly with the increase of Se concentration. Under the concentrations of Cd1, Cd2 and Cd3, Se content of polished rice with Se2 treatment were decreased by 3.4,3.2,2.7 compared to SeO. When added Cd concentration was higher than 2 mg/kg, Se distribution portion in polished rice got higher with the increase of Se concentration; When added Cd concentration was 4-8 mg/kg, Se distribution portion in polished rice increased as Se concentration raised.3. N content in leaf, sheath, root and stem decreased with the increase of Se concentration under same Cd concentration.P content in leaf, stem, sheath and rice bran with the increase of Se concentreation under 2-4mg/kg Cd concentration, K content in sheath, root, stem with the increase of Se concentreation under 2-4mg/kg Cd concentration. At the mature stage, under the concentrations of Cd1, Cd2 and Cd3, N content and accumulation of polished rice with Se2 treatment were decreased by 11.97% and 17.95%,12.52% and 29.17%,9.43% and 18.89% compared to SeO; P content and P accumulation of polished rice with Se2 treatment were decreased by 36.56% and 44.55%,36.12% and 49.12%,27.34% and 40.68% compared to SeO; K content and K accumulation of polished rice with Se2 treatment were decreased by 7.77% and 13.97%,5.69% and 11.35%,3.85% and 21.75% compared to SeO. With the increase of Se concentration under same Cd concentration, N distribution portion in leaves, stem and heaths, root decreased, N distribution portion in grain increased; P distribution in leaves and stem and sheaths decreased, P distribution in roots increased; K distribution in stem and sheaths and grain decreased, K distribution in roots increased.4. With the increase of Se concentration under same Cd concentration, Fe content of stem increased, Zn content of stem decreased; Cu,Fe,Mn content of leaf increased; Cu,Zn of root decreased, Fe, Mn of root increased; Cu,Fe,Mn content of sheath increased, Zn content decreased; Cu,Fe,Mn,Zn of rice husk and polished rice increased; Cu,Fe,Mn of rice bran increased, Zn content of rice bran decreased. With the increase of Se concentration under same Cd concentration, Cu accumulation of root, rice bran, polished rice decreased, Cu accumulation of rice husk increased; Zn of stem and sheath increased; Fe and Mn of root increased; Zn, Fe, Mn of rice bran.polished rice, rice husk increased.5. Dry matter in different organs of rice decreased with the increase of Se concentration under the same Cd concentration. At the mature stage, Under the concentrations of Cd1, Cd2 and Cd3, dry matter of stem and sheath with Se2 treatment was in the range of 3.88%-5.80%, dry matter of root with Se2 treatment was in the range of 12.40%-27.57%; dry matter of spick with Se2 treatment was in the range of 3.88%-15.38%; dry matter of leaf with Se2 treatment was in the range of 15.09%-17.04%.Yield of rice with Se2 treatment were increased by 3.03%,7.20%, 10.29%P<0.01) compared to SeO. |
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