Characteristics Of Rhizosphere Soil Nutrients And Arbuscular Mycorrhizal Fungal Communities In Different Families Of Chinese Fi

Cunninghamia lanceolata is not only the main afforestation and fast-growing commercial timber forest in southern China,but also the main development tree species in the planning and construction of national wood strategic reserve production base,which plays an extremely important role in forest resources construction and ecological development.In recent years,in the process of afforestation of Cunninghamia lanceolata plantation in China,long-term continuous planting and pure forest construction caused soil microenvironment imbalance and decreased ability to inhibit pathogens,resulting in a decrease in the number of fungi and nutrient cycling efficiency in the soil.in turn,the problems such as the decline of soil fertility and productivity have seriously affected the sustainable development of Chinese fir plantation management in China,which urgently needs to be solved.Cunninghamia lanceolata is a typical symbiotic species of arbuscular mycorrhizal fungi(arbuscularmycorrhizalfungi,AMF).The mycorrhizal symbionts formed are of great significance to the growth of Cunninghamia lanceolata.However,the relationship between rhizosphere soil nutrients and AMF community structure in different families of Cunninghamia lanceolata has not been fully explained.In this study,based on the growth characteristics of progeny,families with high growth(H),low growth(L)and normal growth(CK)were selected to analyze the relationship between rhizosphere soil nutrients,AMF community and individual growth performance by studying growth and physiological characters,rhizosphere soil nutrients and root AMF community structure of Cunninghamia lanceolata.The interaction mechanism between fast-growing families of Cunninghamia lanceolata and soil microenvironment was preliminarily revealed,which provides a theoretical basis for further exploring the interaction between the growth of improved varieties of Cunninghamia lanceolata and the structural characteristics of microorganisms in the site environment.The main conclusions are as follows:1)There are differences in phenotypic characteristics among families with different growth rates of H,L and CK.The tree height and DBH of H,L and CK increased more in summer,but became slower in autumn and winter.The contents of starch,soluble sugar and NSC in the leaves of different growth families decreased at first and then increased from June to December,among which the content was the lowest in August and reached the highest level in December.DBH was positively correlated with starch and NSC content,and negatively correlated with soluble sugar content.Tree height was positively correlated with starch,soluble sugar and NSC content,and significantly positively correlated with DBH.2)The contents of T-GRSP,total nitrogen,total phosphorus and organic carbon in rhizosphere soil of H,L and CK families were different in different months.The contents of T-GRSP,total nitrogen,total phosphorus and organic carbon in rhizosphere soil of different families of Cunninghamia lanceolata in summer(June and August)were higher than those in autumn and winter(October and December),higher in August and lower in October.Except that the content of organic carbon in CK was lower than that in L in June,the contents of total nitrogen,total phosphorus and organic carbon in CK were always higher than those in H and L families from June to December.The contents of organic carbon and total phosphorus in H family were lower than those in L family in June and August,and higher than those in L family in August and October.The contents of total nitrogen,organic carbon and total phosphorus in rhizosphere soil were positively correlated with each other,while T-GRSP was positively correlated with total nitrogen and organic carbon,and negatively correlated with total phosphorus content.3)The AMF community of H,L and CK families showed a community structure of "the same dominant genera,but relatively rich and different" at the family and genus level from June to December.AMF community comes from 5 orders,8 families and 10 genera,there are40 species,a total of 320 OTU.The dominant genus is Glomus,and the relative abundance in H,L and CK is 99.01%,97.1% and 99.56%.Followed by Acaulospora and Diversispora.Paraglomus is only distributed in H and L,and Ambispora is only distributed in CK.The results showed that AMF had a preference for the selection of host plants,and the composition of AMF community was different among different provenances.The number of OTU contained in H,L and CK was 236,257 and 231 respectively,and the number of endemic OTU was 24,42 and 16 respectively.The results showed that the diversity of AMF community in H and L was more abundant than that in CK.There were differences in AMF community composition among different families of Cunninghamia lanceolata in different months.The AMF communities in June,August,October and December came from 4 families and 4genera,7 families and 9 genera,7 families and 8 genera and 4 families and 4 genera,respectively.In different months,the dominant families and genera are all Glomeraceae and Glomus,but the relative abundance is different.4)The richness and diversity of AMF communities in H,L and CK families were significantly different in different months.The changes of ace,Chao and sobs index of H and L with time from June to December the richness of AMF community increased,while CK decreased,the lowest values of H and L index appeared in June and August,and CK appeared in December.The results showed that the change trend of AMF community richness in H and L was the same,and the community composition of AMF was more similar.The lowest values of shannon and simpson index of species diversity appeared in H12 and L6,which may be the strategy of AMF community to cope with environmental change.T-GRSP,starch,soluble sugar,total phosphorus,total nitrogen and DBH are all important factors affecting the composition of AMF community.Among them,T-GRSP,soluble sugar,starch,total phosphorus and total nitrogen had great influence on the composition of AMF community.The top 4 genera of AMF community abundance are Glomus,Acaulospora,Gigaspora and Diversispora.Acaulospora preferred to the soil with high content of total phosphorus and total nitrogen,and had little effect on the growth of DBH.