| With the rapid development of industry and agriculture, a large area of farmland affected by heavy metals especially Cd, Pb pollution. In order to guarantee the safety in production of agricultural products, the screening and breeding crop varieties with low Cd、Pb accumulation is believed as one of the most reasonable and effective pathways for Cd, Pb pollution in soils.The pot-culture experiments were conducted to investigate different cultivars in absorption, accumulation and transport of Cd and Pb in Chinese soybean cultivars, and selected the low accumulation of Cd and Pb cultivars. Screening of the Cd, Pb low accumulation of soybean varieties were further studies on its response to Cd, Pb stress and its growth and accumulation characteristics under Cd-Pb compound pollution.In the pot-culture experiment, Cd concentrations in seed were significant (P<0.05) differences among the 25 soybean plants.The mean values of Cd concentration were 0.44 and 0.81 mg kg-1 DW under 2 Cd treatments(1.0 and 2.5mg kg-1), respectively.The standards for the selection of low Cd accumulator include:(1)Cd concentration in their edible organs should be lower than relative standard; (2)Enrichment Factor<1.0; (3)Translocation factors< 1.0; (4)they can tolerate Cd when growing in polluted soils as measured by seed biomass. The cultivars Shennong 10 Tiefeng 31, Tiedou 36, Tiefeng 37 and Liaodou 21 could be selected as Cd excluder soybean cultivars and their quality was further investigated. Our results indicated that Cd concentration in soil disturbed the uptake of mineral nutrient elements by inhibiting the uptake of Ca, Cu and Mn and by enhancing the accumulation of Zn and Fe in the seeds of the five soybeans Cd excluder cultivars.The seed Pb concentrations under three Pb treatments (500,1000 and 2000mg kg-1) varied significantly (P<0.05), with average values of 0.20,0.25 and 0.33 mg kg-1, respectively. The standards for the selection of low Pb accumulator include:(1)Pb concentration in their edible organs should be lower than relative standard; (2)Enrichment Factor<1.0; (3)Translocation factors<1.0; (4)they can tolerate Pb when growing in polluted soils as measured by seed biomass. Cultivars Shennong 6, Shennong 8, Tiefeng 29, Tiefeng 37, Ji 1005, Liaodou 15 and Suke 1 were found to fit the criteria for Pb excluder cultivars. The seeds of these seven cultivars were further assessed for interactions between Pb and other mineral nutrient elements such as Ca, Cu, Fe, Mg, Mn and Zn. High lead concentration in soil was found to inhibit the uptake of Ca, Cu, Fe, Mg and Zn. Furthermore, Mn accumulation was found to be enhanced in the seeds of all of the seven Pb excluder cultivars in response to high Pb concentration.In different Cd and Pb stress, the biomass of soybean increased at low concentrations, but decreased at high concentration, and the change was not significantly different (P>0.05).With the increase of Cd concentration, Tiefeng 31 and Hefeng 40, its SOD activity showed a trend of decreased first and then increased and then decreased with SP content; Hefeng 40 in leaves increased gradually, while the Tiefeng 31 leaves SP content first increased and then decreased. With the increase of Pb concentration, Shennong 6, and Kaiyu 13 SOD activity was increased firstly and then decreased; the content of SP Shennong 6 in leaves decreased, while SP content in leaves of Kaiyu 13 in the concentration of Pb was decreased by 100 and 500mg kg-1, to 300mg kg-1 when the concentration of Pb.Four soybean cultivars under Cd-Pb compound pollution showed high tolerance, in the following order:Tiefeng 31> Kaiyu 13> Hefeng 40-Shennong 6. At the same time, Tiefeng 31 for low Cd accumulator in soybean cultivar also exhibited low accumulation of Cd-Pb under Cd-Pb compound pollution condition. |
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