Impact of phosphate solubilizing and mineralizing bacteria on phosphorus acquisition, symbiosis and yield of chickpea
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
Phosphorus (P) the most essential nutrient exists as immobile ion in the soil and its availability to plants is greatly influenced by Phosphate Solubilizing and Mineralizing Bacteria (PSMB). In the present study 17 PSMB isolates from chickpea rhizosphere were screened for various phosphate solubilizing, mineralizing and plant growth promoting activities. On NBRIP and Pikovskaya’s (PVK) media, maximum qualitative P solubilization was recorded with isolate RB-1 and RB-3 with Phosphate Solubilizing Index (PSI) 2.28 and 1.88, respectively. Significantly high quantitative P solubilization was recorded with isolate RB-3 (16.51 mg/100 ml) in PVK broth. Highest Phosphate Mineralization Index (PMI) was recorded with isolate RB-1 (2.31) followed by RB-3 (2.1). Quantitatively highest P mineralization was observed with isolate RB-1. Total of 38.9 and 61.1% PSMB isolates were found positive for organic acid production with MR and VP test, respectively. Significantly high acid and alkaline phosphatase activities were observed with isolate RB-2 and RB-1 (115.4 and 261 µg p-nitrophenol/ml/hr, respectively). Highest phytase activity was observed with PSMB-4 isolate. Significantly high immobilized P was recorded in isolate RB-3 (0.26%) which was statistically at par with RB-6 (0.26%). Isolates RB-1 and RB-4 were found resistant to ampicillin and tetracycline. Significantly high IAA production was noticed with isolate RB-3 (46.14 µgml-1) followed by RB-2 (44.78 µgml-1) in the presence of tryptophan. Highest zinc solubilization was shown by PSMB-3 (1.53 and 1.2 cm as halo zone) on trisminimal and ZnO2 media respectively. Highest siderophore production was observed with isolate RB-3 with halo zone of 0.75 cm. Three best PSMB isolates (RB-1, RB-2 and RB-3) were evaluated in vivo along with Mesorhizobium and 4 grades of phosphorus (0, 20, 30, 40 kg P2O5 ha-1) for P acquisition, symbiosis and yield of chickpea. For all growth, symbiosis, soil quality and yield parameters, enhanced performance was observed with CBF3+40 Kg P2O5 ha-1 followed by CBF1+40 Kg P2O5 ha-1 and CBF2+40 Kg P2O5 ha-1 over uninoculated control.
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