Occurrence and distribution of arbuscular mycorrhizal fungi and microbial flora in the rhizosphere soils of mungbean [vigna radiata (L.) wilczek] and soybean [glycine max (L.) Merr.] from Adilabad, Nizamabad and Karimnagar districts of Andhra Pradesh state, India

Abstract

Arbuscular Mycorrhizal (AM) fungi are key components of soil microbiota and obviously interact with other microorganisms in the rhizosphere which is the zone of influence of plant roots on microbial populations and other soil constituents. The microbial associates are more prone to general and annual fluctuations besides several abiotic factors such as environment and climatic factors which influence the whole process of AM - microbial interactions. Keeping in view, the importance of AM fungi the present study was undertaken for assessing the AM fungal spore population dynamics in the rhizosphere soil and its colonization, microbial (bacterial and fungal) population distribution in rhizosphere and nonrhizosphere soils as a function of seasonal variation in relation to soil physico-chemical factors associated with two legume crop plants collected from different districts of Andhra Pradesh state, India. AM fungal propagules and species were found to be well distributed varying in number from 12 to 89 spores per 10 gram soil in mungbean and 46 to 90 spores in soybean rhizosphere soils and percent root colonization in mungbean ranged from 36.74 to 90.68% however, in soybean it ranged from 23.58 to 76.92%. The 24 AM fungal species representing 4 genera were isolated, Glomus represented 12 spp. forming predominant genus. The Pearson Correlation coefficient data showed that the microbial population and AM fungal population and species, the degree of root colonization by native AM fungi varied significantly in two legume crop plants and influenced by soil edaphic factors. Significant negative correlation was recorded between root colonization and mean spore density of both the crops indicating that low levels of spore density are associated with high root colonization. The quantity and type of AM propagules also affected the dynamics of root colonization, which were also increased by increase in age of the crop plant.