No abstract

No abstract

Summary Among several phosphate-solibilizing micro-organisms isolated from an alluvial soil (Fluvaquent) in sucrose-Ca3(PO,~) 2 agar plates, two fungal strains, ACF2 (Aspergillus eandidus) and ACF Z (A. fumigatus) two bacterial strains, ACB s (Baeillusfirmus B-7650) and ACB~ (B. firmus B-7651) and one actinomycete strain, ACSo (Streptomyces sp.) were efficient solubilizers, solubilizing 297.0, 288.3, 49.0, 45.8 and 29.0 p.g of P as free PO4 -3, respectively, containing 15 mg insoluble P from Ca3(PO4) 2 in broth. Solubilization was lesser from A1PO 4 and FePO 4. The isolates producing oxalic and tartaric acids without or with citric acid showed higher ability of solubilizing insoluble inorganic phosphates.All the above isolates possessed the ability of solubilizing rock phosphate in considerable amounts, ACF 1 (A.fumigatus) being the highest (31.5 p.g), while ACB 6 (B.firmus B-7651) and both the aspergilli also possessed cellulose-decomposing ability in addition. Inoculation of the isolates, in a flask culture experiment, had no significant effect on the accumulation of available phosphorus in soil even when amended with rock phosphate (RP), farm yard manure (FYM), (FYM + RP), rice straw (RS) and (RS + RP). Nevertheless, the overall performance ofACF 2 (A. candidus) and ACB 6 (B.firmus B-7651) was better than that of the others, in this respect, while ACB 5 (B. firmus B-7650) and ACF 1 (A. fumigatus) intensified the enhancing effect of FYM and RS. Partial sterilization, by autoclaving, of the soil had no significant effect on available phosphorus content of the soil irrespective of any inoculation.

No abstract