Ecological And Physiological Research Of Plants In Coal Gangue Heaps

Arbuscular mycorrhiza(AM)fungi are important soil microorganisms in terrestrial ecosystems.They are widely distributed in various ecosystems and can form mycorrhizal symbiosis with more than 90% of the terrestrial plant roots.AM fungi can not only effectively promote the absorption of mineral nutrients by plants and reduce the abiotic stress of plants,but also play importants roles in vegetation succession and restoration in ecosystems.The Vetiveria zizanioides L.community with different planting years(6 a,10 a,14 a and 17 a)in coal gangue mountain were selected as the research subject,which loaced at Dapan Coal Mine in Liupanshui of Guizhou Province.Rhizosphere soil and root samples were collected to analyze the infection characteristics and diversity of AM fungi by methods of dyeing microscopic examination,morphological identification and molecular biological identification.After that,the community compositions of AM fungi and the relationships among the season,planting years,soil factors and AM fungi diversity in the rhizosphere soil and root of V.zizanioides based on Illumina Mi Seq sequencing.Finally,the effects of inoculation with different AM fungi on the growth,photosynthesis,antioxidant enzymes,soluble protein content and the absorption of heavy metal elements of V.zizanioides in coal gangue matrix were conducted by pot experiments.The main results are as follows:(1)6 generas and 48 species of AM fungi were isolated and identified in rhizosphere soil of V.zizanioides in the 4 different planting years by method of morphological.There were 28 species belonged to Glomus,accounting for 58%;12 species belonged to Acaulospora,accounting for 25%;5 species belonged to Scutellospora,accounting for 10%,and other genera each had 1 species,accounting for 2%.Glomus and Acaulospora were the dominant genus in this study.The evenness,Shannon index and Simpson index were reached the maximum value at 10 a.The planting years was extremely significantly positively correlated with species abundance(P<0.01).(2)It was found that the root system of V.zizanioides could establish a good mutually beneficial symbiotic relationship with AM fungi and forming an arbuscular mycorrhizal structure by staining microscopic examination.The AM infection rate of vetiver root system was 48.66?77.65%,which increased first and then decreased with the increase of planting years.The soil spore density is 104.33?496.67 per/10 g soil,and it tends to decrease first and then increase with the increase of planting years.(3)Correlation analysis showed that spore density had a very significant positive correlation with soil available potassium and p H(P<0.01),and had a very significant negative correlation with soil organic matter,total nitrogen and total phosphorus content(P<0.01).The infection rate was significantly positively correlated with soil organic matter,total nitrogen and p H(P<0.05),and significantly negatively correlated with total potassium(P <0.05).(4)A total of 295 AM fungal OTUs were obtained from rhizosphere soil and root samples of V.zizanioides by high-throughput sequencing,while 258 OTUs in the roots and 175 OTUs in the rhizosphere soil,repectively.They belong to Acaulospora?Dominikia?Diversispora?Funneliformis?Glomus?Paraglomus?Rhizophagus?Septoglomus?Scutellospora and unidentified?Glomeromycota.There were differences in the composition of AM fungal communities in rhizosphere soil and roots,and the seasons and years of planting have significant effects on the composition of AM fungi community in rhizosphere soil and root system.Spearman correlation analysis showed that the ACE index in root samples was significantly negatively correlated with total nitrogen and p H(P<0.05),and extremely significantly positively correlated with total potassium(P<0.01).The Shannon index of the rhizosphere soil samples showed a significant negative correlation with p H(P<0.05).RDA analysis showed that p H had the most significant impact on the diversity of AM fungi community in the rhizosphere soil,while the contents of available phosphorus and total phosphorus had the most significant impact on the diversity of root AMF community in the root system.(5)The results of the pot experiment showed that the that mycorrhizal structure were observed in four inoculation treatments with Glomus versiforme(G.v),Glomus etunicatum(G.e),Glomus mosseae(G.m),and Acauloapora scrobiculata(A.s),which had a higher colonization at 42.22%?71.11%.All treatments increased the chlorophyll and soluble protein content,POD and SOD activity while decreased the MDA content of V.zizanioides.Compared with CK,underground and aboveground biomass of V.zizanioides treated with G.m increased by 159.37% and 118.93%,respectively.Compared with CK,the four inoculation treatments all reduced heavy metal concent in the underground parts,but the content of aboveground increased.