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Modulating rhizosphere colonisation, plant growth, soil nutrient availability and plant defense enzyme activity through Trichoderma viride-Azotobacter chroococcum biofilm inoculation in chickpea

Velmourougane, Kulandaivelu, Prasanna, Radha, Singh, Surender, Chawla, Gautam, Kumar, Arun, Saxena, Anil Kumar
Plant and soil 2017 v.421 no.1-2 pp. 157-174
Azotobacter, NPK fertilizers, Trichoderma, biofilm, chickpeas, enzyme activity, enzymes, exudation, nutrient availability, proteins, rhizoplane, root shoot ratio, roots, scanning electron microscopy, shoots, soil, soil nutrients, staining
AIMS: Establishment of inoculated biofilms on root surfaces and their effect on plant enzyme activities and nutrient availability in the rhizosphere are less investigated. Two beneficial inoculants- Trichoderma spp. and Azotobacter spp., and the biofilm developed using them as partners, were evaluated in chickpea crop. The hypothesis tested was that the efficacy of the fungal-based bacterial biofilm in colonizing the root and rhizosphere may be better, as compared to their individual inoculation. METHODS: Scanning electron microscopy and root staining illustrated the colonisation of developed T. viride (Tv) – A. chroococcum (Az) biofilm and their partners. Inoculation effects were analysed on selected plant growth parameters, soil nutrients, plant enzyme activities and organic acid exudations in the rhizosphere soil. RESULTS: Tv-Az biofilm was observed to exhibit better colonization in the rhizosphere and rhizoplane of chickpea, as compared to single inoculation. Significant enhancement of 30–45% in root volume, root proteins, root-shoot ratio, exudation of succinic and fumaric acids, soil available nutrients, along with two fold enhancement in the activity of plant enzymes was recorded, as compared to recommended doses of NPK fertilizers. CONCLUSIONS: Tv-Az biofilm is a promising biofertilizing option for enhancing plant growth parameters, available soil nutrients, along with providing a savings of 25% nitrogenous fertilizers in chickpea.