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.

The present experiment provides information on the phosphorus compounds in rice seeds and elucidates the changes they undergo during germination. In ungerminated seeds, the bulk of total‐P appears in phytin (about 76 per cent). It is then dephosphorylated in course of germination with a simultaneous accumulation of large amounts of inorganic‐P. Lipid‐P increases very rapidly from 0 to 24 hours. The increase up to 72 hours is gradual, after which it drops at 96 hours and again rises to a maximum after 120 hours. The ester‐P and RNA‐P, fractions increase in concentration with time of germination (except 120 hours). Protein‐P begins to fall after 48 hours, while DNA‐P remains more or less constant throughout the experiment. The two pH optima recorded for phytase activity at 4.0 and 9.0, suggests that there exist two phytases, one acidic and the other alkaline. Both behave similarly during germination with a continuous increase throughout the course of the experiment. The enzyme with an optimal pH at 4 hydrolyses phytin more actively than the other with the pH optimum at 9.0. Phytase shows maximum activity at a stage when most of the phytin has disappeared; the metabolic significance is uncertain.

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Experiments were carried out wltti viable and nonviable rice seeds to detect tlie nature of germination inhibitors.An at)scisic acid tike factor is present iu nonviable seeds but absent in viable ones. The main .source of the factor is the emliryo altliouyh measurahlc amounts are also obtained from ttie husk: it i.s not found in the endosperm however. Interaction with GAg and IAA suggests that both the rice seed inhibitor and abscisic acid are antagonistic to GA;( and partially reversed the IAA induced growtti. The similarity of the UV absoiption s|»ectra of the inliiliitor and ahscisic acid also proves ils presence in nonviable seeds. The inhibitor .suppresses tbe a-amytase activity Ixith in intact unit excised seeds in the same way as abscisic acid but the suppression is partialty iivercome witb hif^her concentrations of GAg.