The Effect Of Plant Endophyte On Tolerance And Enrichment Of Heavy Metals Of Oil Sunflower In Jingchang Mining Area

Due to human production activities,a large amount of heavy metals are deposited in the soil,which results in changes in the physical and chemical properties of the soil,reduced fertility,inability to be used for cultivation,and eventually endangering human health through the food 1chain.Therefore,the treatment of soil heavy metal pollution is one of the world's most urgent problems to be solved.Phytoremediation is theoretically the green,economic,and most practical method for the treatment of heavy metal pollution.However,due to many factors such as slow plant growth and long growing period,the phytoremediation method has little effect in actual pollution control applications.Plant endophytes are fungi or bacteria that live in plant tissues at a certain stage or during the entire life cycle.They interact with plants and do not produce significant negative effects on plant tissues.A large number of studies on the combination of plant endophytes and plants to remedy heavy metal contamination have shown that endophytes can not only help plants extract heavy metals from the soil,thereby restoring contaminated soil,but also promote plant growth and development.The oil sunflower(Helianthus annuus Linn)of oil crop has strong heavy metal accumulation capacity,large above-ground biomass,and the seeds can be processed into edible oil or biodiesel after detoxification with heavy metals,and has high economic value,and is suitable for phytoremediation of heavy metal pollution land.This study focused on the pollution status of the Cu and Ni mining areas in Jinchang City,Gansu Province.The indigenous plant species in the area were used as research objects to determine the Cu and Ni enrichment of plants,and the endophytes were isolated and identified.And a variety of growth-promoting traits to promote endophytes and determine their resistance to oil sunflower tolerance and enrichment of soil heavy metals and oil sunflower growth and development of the strengthening and promoting role in the establishment of a feasible plant-endophyte combination Repair of heavy metal pollution in mining areas provides a demonstration of technology.Experimental results show:(1)Principal components analysis of 18 kinds of endogenous bacteria resistant to Cu and Ni heavy metals were carried out.N1(Pantoea)and W1(Pseudomonas)were finally selected for potted plants that were later treated with oil sunflower to repair soil heavy metal pollution.experiment.N1 belongs to the genus Pantoea and has strong characteristics of producing IAA,activating Cu,activating Ni,and resisting Cu.W1 belongs to the genus Pseudomonas and has strong production of ACC deaminase,phosphorus dissolving,activated Cu,and resistance to nitrogen.Ni and Cu tolerance.(2)The seedling emergence rate of oil sunflower seed was measured in four different concentrations of heavy metals in the control,Xipo,Lao tailings dam and slag.It was found that with the increase of soil heavy metal concentration,the seedling emergence rate of oil sunflower seed was gradually reduced(p< 0.05),but seed germination rate was higher in the Xipo soil than in the control group without heavy metal,indicating that the Cu / Ni heavy metal concentration in the Xipo soil is conducive to the germination and growth of the oil sunflower seed.(3)Experimental treatment Set different soil heavy metal concentrations,different endogenous bacterial colonization times,different inoculums,and determine dry weights above and below the roots of the harvested sunflower oil.It was found that with the increase of soil heavy metal concentration,the combined bacteria N1-W1 The growth promoting effect of oil sunflower was better than that of single bacteria,and the root biomass of oil sunflower under each heavy metal concentration was greater than that of the non-sterilized control group,but the difference was not significant(p<0.05).(4)Different concentrations of soil heavy metals,different colonization times of endophytic bacteria,and different inoculum treatments were used to determine the contents of three plant hormones IAA,GAs and ABA in the oil sunflower seedlings.It was found that as soil heavy metal concentrations increase,W1 The content of IAA in the above-ground oil sunflower increased first and then decreased,and the difference was significant.The contents of GAs in the aboveground part of oil sunflower under N1 and W1 treatment were higher than that of the combined bacteria,but there was no significant difference between the two species.The ABA content showed a trend of decreasing first and then increasing.The ABA content in shoots of oil sunflower treated with the combined bacteria in low-concentration heavy metal soil was significantly different from that in the treatment of single bacteria,but there was no significant difference in high-concentration heavy metal soils.(p<0.05).(5)The change of soil pH in the rhizosphere of oil sunflower under experimental treatment was measured.With the increase of soil heavy metal concentration,the soil pH in the rhizosphere of plants treated with each strain was not the same,and the pH under the treatment of combined bacteria N1-W1 in the control soil.The decline was even greater.The organic acid excretion of N1 in the soil of the Xipo and Laowei tailings dams was more pronounced,while the pH of the rhizosphere soil of the slag-bearing soil without the addition of the oil sunflower was lower.(6)Cu and Ni enrichment levels were measured on the ground and roots of three harvested oil sunflowers,and it was determined that the concentration of Cu,Ni in the soil increased with the increase of the number of colonization days of endogenous bacteria at different concentrations of heavy metals.,Enrichment coefficient and transfer coefficient.The results showed that: With the increase of soil heavy metal concentration,the accumulation of Cu in the aboveground oil was higher than that of the single bacteria treatment.The Cu accumulation in the root of oil sunflower was higher than that of the single bacteria W1 and the combined bacteria treatment.,but the difference is not significant.With the increase of soil heavy metal concentration,Ni enrichment of shoots and roots of single sunflower N1 treated oil sunflower was larger.The study found that the endophytic bacteria N1 and W1 isolated from the plants grown in the Jinchang Cu and Ni mining areas and the combination of the two formed N1-W1 can promote the growth and development of the oil sunflower in the soil contaminated with heavy metals and increase the oil sunflower Heavy metal tolerance enhances the enrichment and transport of heavy metals by sunflower oil.