| When Chinese fir forest is planted in a large area,the problem of soil quality degradation under the forest is more and more obvious.In view of the problems existing in the management of Chinese fir forest,it is considered that the key measures to solve the problems are to build mixed forest.At present,most of the mixed species are judged by their phenotypic characteristics,and the research on the microbial communities that are interdependent with the trees is not sufficient.Therefore,we extracted the arbuscular mycorrhizal(AM)fungal DNA from the fine roots of Cunninghamia lanceolata in different growth stages,different forest types and natural forests,obtained the gene sequence of AM fungi by high-throughput sequencing of Illumina,and classified them into operational units(OTU)by clustering,and compared with Genbank and Maarj AM.The characteristics of AM fungal community of Cunninghamia lanceolata and its relationship with tree growth and environmental factors were analyzed.We also studied the effect of AM fungi on the growth of Chinese fir seedlings by using the rhizosphere soil of Chinese fir at different growth stages as AM fungal additive.The research provides the basis for solving the decline of Chinese fir woodland capacity and the selection of mixed species.The main results are as follows:(1)There are abundant arbuscular mycorrhizal fungi resources in Chinese fir forest,including 3 orders of Glomales,Archaeosporales and Diversisporales,5 families of Glomeraceae,Archaeosporaceae,Acaulosporaceae,Gigasporaceae and Diversisporaceae,6 genera of Glomus,Archaeospora,Acaulospora,Gigaspora,Diversispora and Scutellospora.Among of them,Glomus dominated the community.(2)Chinese fir had different arbuscular mycorrhizal fungi community in different growth stages.There was significant difference between the arbuscular mycorrhizal fungi community of young Chinese fir and that of other growth stages.The number of arbuscular mycorrhizal fungi in the rhizosphere of Cunninghamia lanceolata was the most in the near mature stage.The community of arbuscular mycorrhizal fungi was the most stable in the mature stage of Chinese fir,indicating that the associated microbial community was also the most stable in the mature stage of Chinese fir,which was the best cutting period.(3)There were significant differences among the microbial communities in different forest types.Compared with pure forest,the species and quantity of arbuscular mycorrhizal fungi in mixed forest were less,which indicated that the change of forest type will cause the change of microbial community under the forest.The growth of Cunninghamia lanceolata × Pinus massoniana mixed forest lags behind that of Cunninghamia lanceolata × Phyllostachys pubescens mixed forest.Because Pinus massoniana is an ectomycorrhizal tree species,and there is a symbiosis of arbuscular mycorrhizal fungi in the rhizosphere of Phyllostachys pubescens,which showed that the symbiosis of tree species depends on the symbiosis of their rhizosphere microbial community.(4)The arbuscular mycorrhizal fungi community of natural Chinese fir forest was more abundant than that of artificial Chinese fir forest.The results showed that the fungi of Scutellospora only appeared in the natural Chinese fir forest,which indicated that the fungi of Scutellospora may be the key population in the near natural management of the artificial Chinese fir forest.(5)At the age of 18 months,the ground diameter of Cunninghamia lanceolata seedlings began to significantly grow,while the height,root length and biomass of Cunninghamia lanceolata seedlings did not grow significantly at the early stage,but increased significantly at the age of 13 months.The results showed that the growth of ground diameter was slow in seedling,and the growth of seedling was mainly in height and biomass.After AM fungi infecting the root system of host plant,the growth of host plant changed significantly.Among them,the changes of ground diameter,seedling height and root length were more obvious at the early stage(7 months old),and then the difference of growth decreased.However,the biomass accumulation of seedlings always increased significantly after the AM fungi inoculation.There was no significant difference in the effect of different AM fungi on the ground diameter,height and root length of seedlings,but only on the biomass accumulation of seedlings.(6)Plant growth stage,stand type and environmental factors are closely related to the changes of AM fungal community. |
PDF Full Text Request