Study On The Promoting-Growth Mechanism Of Arbuscular Mycorrhizal Fungi And Their Community Structure In Acer Truncatum Rhizosphere

Acer truncatum,a high-benefit economic tree,grows slowly in most of planting area and their seed yield is also very low due to lack of excellent variaties,which maks it hard to meed the market demand.How to improve A.truncatum growth is becoming one of the most important questions for the A.truncatum development.Arbuscular mycorrhizal(AM)fungi can form symbiosis with more than 90% of terrestrial plants and their beneficial effect on most plants has been pointed OTU.However,the effects of AM fungi on A.truncatum growth and their relevant mechanism have not been fully revealed.Thus,in this study,we firstly selected A.truncatum trees with different traits(elite and ordinary tree)in the same planting area or the same trait(ordinary tree)in different planting areas to calrify A.truncatum growth status,AM fungal characteristics and their relationships,and then,in the greenhouse,we measured the effects of AM fungi(Rhizophagus intraradices)on the decomposition of A.truncatum dead leaves and their relationship with the A.truncatum growth,which lays a foundation for the application of mycorrhizal technology in the development of A.truncatum industry.The main results are as follows:(1)In the same planting area,soil pH value,root total nitrogen and root total phosphorus contents of elite trees of A.truncatum were significantly higher than ordinary trees.While tree height,leaf total nitrogen,leaf total phosphorus,leaf total potassium,rhizosphere soil ammonium nitrogen,nitrate nitrogen,available phosphorus,available potassium and organic carbon contents of ordinary trees were significantly higher than elite trees.According to the characteristics of AM fungi,the mycelium density and Chao index of AM fungi in rhizosphere of elite trees were significantly higher than ordinary trees.The co-occurrence network topology of AM fungi community in root and rhizosphere of elite trees was more complex than ordinary trees.The differences between them were found to be mainly concentrated in A.truncatum root.There was a significant correlation between AM fungal community diversity and total phosphorus content in A.truncatum root.Rhizosphere soil AM fungal community diversity was significantly correlated with tree height,diameter at breast height,soil available phosphorus,organic carbon and pH;among them,soil available phosphorus and organic carbon content were significantly and positively correlated with ordinary trees AM fungal community diversity,and tree height,diameter at breast height and soil pH were significantly and positively correlated with euphorbia AM fungal community diversity.(2)There were significant differences in tree height,diameter at breast height,root and leaf nutrients,soil total nitrogen,total phosphorus,total potassium,ammonia nitrogen,available phosphorus,available potassium,organic carbon and pH values of A.truncatum in different planting areas,but no significant differences in soil nitrate nitrogen.The AM fungal properties showed significant differences in the spore density,mycelium density and Richness in the rhizosphere,but there were no significant differences in the beta diversity of AM fungal community among different planting sites.Only the dispersion of AM fungal community between FF1 and FF2,FF3,FX,WG4 and ZZ were significant differences.The Richness indexes of AM fungi in the rhizosphere were positively correlated with leaf nutrient status.There was a close relationship between AM fungal community richness and growth status of A.truncatum in different planting areas.(3)Inoculation with AM fungi significantly increased the contents of dry weight and fresh weight,root total nitrogen,root total phosphorus,root total potassium and leaf total phosphorus in aboveground and underground parts of A.truncatum,and decreased the contents of leaf total potassium,but had no significant effect on plant height,ground diameter and leaf total nitrogen.Inoculated with AM fungi significantly changed the root morphology of A.truncatum,and reduced the proportion of fine roots and increased the proportion of coarse roots.The indices of root morphology and the ratio of coarse root were positively correlated with the contents of biomass,total nitrogen,total phosphorus,total potassium and leaf total phosphorus,and negatively correlated with the proportion of fine root and total potassium.The growth status of A.truncatum was closely related to root morphology.(4)Inoculation with AM fungi significantly increased the total decomposition capacity and the release of polyphenol content,changed the decomposition particle size,and reduced the total nitrogen content of dead leaves,but had no significant effect on the contents of tannin,cellulose,total phosphorus,total potassium and organic carbon.The accumulation of total nitrogen content in dead leaves was positively correlated with total potassium content,and negatively correlated with biomass and other root and leaf nutrient indexes of A.truncatum.The growth status of A.truncatum was closely related to decomposition of dead leaves.