Mycorrhizal status of naturally occuring and cultivated legumes of iron ore mine Wasteland in Goa

Abstract

Fresh iron ore mine rejects are found to be deficient in nitrogen (N), phosphorus (P), potassium (K), and other macro- and micro-nutrients. The organic matter is very low or nearly absent as there is hardly any microbial activity. However, there is no heavy metal toxicity. The electrical conductivity (EC) is also very low indicating that there is no likelihood of salinity problems. The pH of the fresh rejects is neither highly acidic nor alkaline, and therefore, poses no problems for plant growth. Thus, as far as revegetating the mine waste lands is concerned, there is need to select suitable plant species that can thrive under the hostile nutrient-deficient conditions. One such group of plants are the legumes. Legumes play a major role in agriculture by providing high protein grain and improving soil fertility. The leguminous plants can form two types of symbiotic associations with micro-organisms. One with Rhizobium spp. involved in nitrogen fixation, and the other with vesicular-arbuscular mycorrhizal (VAM) fungi, concerned with the uptake of phosphorus and other nutrients. Inoculation of legumes with YAM fungi can stimulate nodulation and nitrogen fixation. The present study was conducted to find out whether the legumes growing on the iron ore mine waste lands were infected by VAM fungi and, if so, to assess the extent of mycorrhizal colonization. The present study concluds that legumes growing on the iron ore mine rejects are infected by VAM fungi. Further identification of these fungi infecting legum nous plants already growing on fairly established iron ore mine wastelands, their multiplication, and proper utilization would bring about early reclamation of recently degraded mintlands in the state of Goa.