Growth of different tree species and their nutrient uptake in limestone mine spoil as influenced by arbuscular mycorrhizal (AM)-fungi in Indian arid zone

The mining and quarrying of mineral ores lead to conflicts between the ideals of economic prosperity and landscape preservation. Rehabilitation/revegetation of mine spoils has received considerable attention in recent years due to acceleration of mining and associated land disturbances. This is an attempt towards rehabilitation of limestone mine spoils in arid areas where water and nutrients are the main constraints even in normal soil. An arbuscular mycorrhizal fungus (AMF), Glomus mosseae was isolated from limestone mine spoils and its effect on the growth and nutrient uptake in different tree species grown on limestone mine spoils as well as rhizosphere effect were examined. Soil inoculation with G. mosseae had significantly enhanced plant growth and biomass production in limestone mine spoils and the enhancement varied from one species to the other. Further, there was an improvement in per cent root infection and AMF spore density in the rhizosphere indicating the establishment of G. mosseae in limestone mine spoil. Activities of various enzymes (dehydrogenase, phosphatases and nitrogenase) and population of nitrifying bacteria and Azotobacter were also improved upon inoculation with AM-fungus besides improvement in the uptake of many nutrients except Na and K. Because of the ability of AM-fungi in improving the water uptake and transport in plants, enhancing the uptake of various nutrients and enabling the plants to withstand high temperatures, AM-fungi native to limestone mine spoils may play a critical role in revegetating these spoils in arid areas. In view of the above results, use of arbuscular mycorrhizal fungi may be adopted for the rehabilitation of limestone mine spoils for creating a better ecosystem.