Remediation effects of plant root growth inoculated with AM fungi on simulation subsidence injured

Coal mining promotes economic development,however,it causes a lot of ecological problems such as surface subsidence and cracks. The plants roots are injured seriously in the processes of subsidence. Then the injured roots im-pact plant growth and physiological processes,and the structure and function of ecological system. It is important to find out more effective way to restore the injured roots. But it is difficult to study roots because they exist in unobserv-able soil. The irregular distribution of roots and the different forces generated in the process of surface subsidence are difficult to be studied comprehensively. The technologies to repair the injured roots of plant have not been completely perfected yet. The traditional physical and chemical technologies have many disadvantages:high cost,time-consuming,laborious and bringing secondary pollution. The arbuscular mycorrhizal fungi (AM fungi) as a safe and green microbi-ological technology are advocated at home and abroad. They benefit for the growth and nutrition absorption of plant, and have a great value and potential to restore the degraded ecology caused by coal mining. In this study,the split root system was used to simulate vertical root injury in mining area. With maize as a host plant,the effects of arbuscular mycorrhizal fungi on the growth and physiology of root-damaged maize were investigated. The results demonstrated that the negative effects of the injured roots on the maize growth was alleviated by the inoculation of AM fungi. The aboveground and belowground biomass of maize with 1 / 3 roots injured inoculated was significantly increased by 43． 8% and 17． 6% respectively comparing with control groups. The aboveground and belowground biomass of maize with 2 / 3 root injured was more than that without inoculation insignificantly. The mycorrhizal colonization and hyphal density of AM fungi were 71． 1% and 4． 82 m / g respectively in mycorrhizal compartment,though the roots were in-jured at highest degree. Inoculation promoted the nutrient uptake of maize with injured roots. When the 1 / 3 roots of maize were injured,the N,P,K,Ca and Mg concentrations of maize shoots maize inoculated increased significantly by 1.55,0． 43,5． 23,2． 81 and 0． 28 mg / g respectively comparing with the control groups,and that of maize roots inocu-lated significantly increased by 1． 32,0． 73,5． 0,6． 45 and 0． 69 mg / g respectively comparing with non-inoculaton, and the AM fungi restored mineral concentrations of maize to uninjured level. The inoculation reduced the adverse effect from injured roots on the endogenous hormones concentrations of maize root. The inoculation increased the indole acetic acid (IAA),gibberellin ( GA),cytokinins ( CTK) and reduced the abscisic acid ( ABA) concentrations of maize with 1 / 3 injured roots significantly,compared with the control groups in mycorrhizal compartment. The endoge-nous hormones concentrations was restored to the uninjured level. The GA and CTK concentration of maize with 2 / 3 injured roots inoculated in mycorrhizal and root compartments restored to the level of endogenous hormone in root with 1 / 3 injured. And the infection rate and hyphal density of AM fungi was significantly correlated with the GA and CTK, and correlated with IAA and ABA of roots insignificantly. The arbuscular mycorrhizal fungi alleviates the adverse effects of injured root on the physiological growth of plants,and provides a good theoretical basis and technological support for the ecological restoration in the mining area,which has ecological significance.