Effects of AMF on the growth of Caragana in simulated compacted soil in mining area

Soil compaction is a common problem in the process of land reclamation in mining area,which has a significant impact on vegetation restoration. In order to study the impact of soil compaction and the inoculation of AM fungi on plant root system development and the nutrient absorption in the aboveground,laboratory simulation experiments have been carried out on caragana. The results show that the soil compactness affected plant root system configuration,mild compaction (C1) promoted root morphological development,severe compaction (C2) inhibited the growth of root system,showing the total root length,average root diameter,root surface area and root volume decreased. The inoculation of AMF could promote the secretion of IAA,CTK and GA hormones in the caragana root system,and the secretion increased with the compaction degree,meanwhile,ABA secretion decreased. The synergy between hormones increase the total root length,average diameter,surface area and volume of the root system. The inoculation of AMF could significantly promote the absorption of nutrients N,P,Fe and Mn in severe compacted soil,and increase the biomass of caragana. Under the severe compaction gradient (C2),the inoculation of AMF could significantly promote the nutrient content of N,P,Fe and Mn in the aboveground part of caragana,and increase the biomass of caragana,compared with CK,the dry weight of the above ground and underground parts of caragana and plant height were increased by 48.08% ,58． 33% and 6. 91% respectively. Root hormone secretion was correlated with root morphological development and nutrient content in the aboveground part. The secretion of root IAA,CTK and GA was significantly positively correlated with mycorrhizal infection rate,mycelium density,and the nutrient content of N,P and Zn in the aboveground. In the compacted soil,the inoculation of AMF could adjust plant root physiological activity,encourage more root growth, increase the host plants of N,P,Fe,Mn,Zn nutrient absorption,to reach the goal of improving plant biomass and soil compaction stress resistance in the compacted soil in mining area,achieving the purpose of efficient ecological restoration.