Inoculation of Arbuscular Mycorrhizal Fungi and Plant Growth Promoting Rhizobacteria in Modulating Phosphorus Dynamics in Turmeric Rhizosphere

Rhizomes of turmeric (Curcuma longa L.) are widely used for their medicinal as well as flavoring properties and in order to concentrate on biological means of promoting turmeric cultivation in Assam, North East India, a greenhouse study was carried out to investigate the effect of arbuscular mycorrhizal fungi association in modulating soil phosphatase activity and phosphorus uptake by plants. The effect of arbuscular mycorrhizal fungi alone and in combination with phosphate solubilizing and nitrogen fixing bacteria was assessed on turmeric rhizosphere and treated plants exhibited an enhanced phosphatase activity of 18.11–21.19 µg p-nitrophenol g−1 h−1 at 90 days and 18.33–21.39 µg p-nitrophenol g−1 h−1 at 150 days after planting and then reduced to 13.89–16.60 µg p-nitrophenol g−1 h−1 at the time of harvest i.e. at 210 days after planting as compared to control. Phosphatase activity showed a rapid increase in dual and consortium inoculation in comparison to mono inoculation. A significantly higher available phosphorus concentration (7.10–8.50 mg kg−1 soil) in rhizospheric soil was observed at 90 days after planting in all the treated plants over control. Total phosphorus uptake by plants inoculated with all the treatment types were significantly higher (21.40–26.32 mg plant−1) compared with the control. This study suggests a synergistic interaction between arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria on phosphorus dynamics in the rhizosphere of turmeric plants.