| Oil plant Ricinus communist L.is often applied in phytoremediation of heavy metals for its good adaptability,heavy metal tolerance and high oil yield.However,high concentrations of heavy metal ions will destroy the normal metabolism of plants,limiting seed germination,and thus seriously affected its growth,survival and remediation efficiency when Ricinus communist L.was used in pyhtoremediation of heavy metals.Aiming at the above situation,in order to realize the efficient germination seeds under Lead-zinc stress,this paper used Ricinus communist L.as tested plants and construct functional microbial consortium to investigate the effects of lead-zinc resistant microbial consortium on seed germination of Ricinus communis L.under lead-zinc stress which was differ from traditional method with pure culture microorganism.The main research contents and results of this paper are as follows:(1)10 fungus and 24 bacterium were isolated from rhizosphere soil of sunflower and pepper which was amended by microbial fertilizer.Srcreening 5 microorganisms(L6?L7?L11?L14 and X8)from 7 microorgamisms with stable shape and good growth according to capacity of plant promoting growth which may be used in construction of microbial consortium.(2)Considering that lead-zinc stress was the key condition in this paper,the construction of microbial consortium should be based on the resistant microorgansisms.The adsorption on Pb2+ and Zn2+ by mixed culture of resistant fungi HA,WB and J3 preserved in our laboratory were investigated by orthogonal experiment.The results showed that the removal rate of Pb21 could reach 91.3%as well as Zn2+ could reach 514%under the optimum conditions by mixed culture X2(HA and J3).It was higher than other mixed culture and could meet the requirements of resistant to lead-zinc stress for microbial consortium.So HA and J3 could be set as the fixed composition strains of microbial consortium.According to studies of research group,resistant fungi HA is Aspergillus oryzae,and resistant fungi J3 is Verticillium insectorum.(3)The antagonistic effects among S screened microorganisms was investigated and the results showed that only L6 with HA and L11 with HA had antagonistic effect.Considering the capacity of plant promoting growth,X8 and L14 was optimized and sequenced.The phylogenetic tree was constructed according to the sequencing results.After BLAST comparison,L14 was identified as Fusarium oxysporum and X8 was Bacillus subtilis.(4)The effects of lead-zinc resistant microbial consortium on seed germination of Ricinus communis L.were studied by sand culture experiment which including the biomass of plants,accumulation of heacy metals and root morphology and gowrth.This paper discussed the role of microbial consortium in seed germination and seedling growth and selected the optimal consortium.The results showed that the addition of microbial consortium could effectively promote the accumulation of heavy metals in plants.Specifically speaking,the accumulation of Pb was increased by 37.1%under the concetraition of 200mg/L as well as the accumulation of Zn increased by 26.9%under the concetraition of 400mg/L by D1 consortium(HA,J3,L14).The cuumulation of Pb was increased by 29.3%under the concentration of 600mg/L as well as the accumulation of Zn was increased by 41.6%under the concetraition of 400mg/L.After comprehensive comparison between microbial consortium D1 and D2 in growth index,root morphology as well as accumulation of heavy metals,the microbial consrtium D2 was selected as the optimal consortium which could be supplied as the microbial consortium in next pot experiment.The results indicate that the microbial consortium could promote seed germination and seedling growth under lead-zinc stress. |
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