An ecological survey was conducted to characterize 4800 bacterial strains isolated from the root-free soil, rhizosphere, and rhizoplane of Prosopis juliflora growing in alkaline soils. Of the 4800 bacteria, 857 strains were able to solubilize phosphate on plates. The incidence of phosphate-solubilizing bacteria (PSB) in the rhizoplane was highest, followed by rhizosphere and root-free soil. Eighteen bacterial strains out of 857 PSB were able to produce halo at 30 degrees C in a plate assay in the presence of 5% salt (NaCl) and solubilize tricalcium phosphate in National Botanical Research Institute's phosphate growth medium (NBRIP) broth, in the presence of various salts, pHs, and temperatures. Among the various bacteria tested, NBRI4 and NBRI7 did not produced halo in a plate assay at 30 degrees C in the absence of salt. Contrary to indirect measurement of phosphate solubilization by plate assay, the direct measurement of phosphate solubilization in NBRIP broth assay always resulted in reliable results. The phosphate solubilization ability of NBRI4 was higher than in the control in the presence of salts (NaCl, CaCl2, and KCl) at 30 degrees C. Phosphate solubilization further increased in the presence of salts at 37 degrees C as compared with 30 degrees C. At 37 degrees C, CaCl2 reduced phosphate solubilization ability of NBRI4 compared with the control. The results indicated the role of calcium salt in the phosphate solubilization ability of NBRI4.http://link.springer-ny. com/link/service/journals/00284/bibs/39n2p89.html

Pseudomonas fluorescens NBRI2650 was isolated after screening 360 bacterial strains from the rhizosphere of chickpea (Cicer arietinum L.) grown in fungal-disease-suppressive field soil. The strain was selected because of its high rhizosphere competence and ability to inhibit the growth of Fusarium oxysporum f.sp. ciceri, Rhizoctonia bataticola, and Pythium sp. under in vitro conditions. Survival and colonization of NBRI2650 in the phytosphere of chickpea, cotton (Gossypium hirsutum L.), cucumber (Cucumis sativus L.), and tomato (Lycopersicon seculentum Mill.) were monitored using a chromosomally located rifampicin-marked mutant P. fluorescens NBRI2650R. The strain showed variable ability to invade and survive in the phytosphere of different plants. Chickpea was used as a tester plant for further work, as it was not invaded by NBRI2650R. The interaction between NBRI2650R and F. oxysporum f.sp. ciceri was studied by both light microscopy and scanning electron microscopy. The lysis of the fungal cell wall by NBRI2650R was clearly demonstrated. Treatment of the chickpea seeds with NBRI2650R in prerelease experiments in the greenhouse using disease-conducive field soils from Jhansi and Kanpur resulted in increased plant growth and did not result in any perturbation of the indigenous microbial community that inhabited the rhizosphere of chickpea compared with nonbacterized seeds. Direct fermentation of diluted NBRI2650R on vermiculite without the need of expensive fermentors offers a reliable process for manufacturing bacterial inoculants in developing countries. Under field conditions, the horizontal and vertical movement of NBRI2650R was restricted to 30 and 60 cm, respectively, and the strain could not survive in the field during the 7 months before the chickpea could be planted for next cropping season. Field trials conducted at Jhansi, Kanpur, and Pantnagar resulted in higher grain yield increase in the bacteria-treated seed compared with the nonbacterized control. Seed and furrow treatment of the two chickpeas ('Radhey' and 'H-208') at Pantnagar resulted in significantly (P = 0.05) greater seedling mortality in nonbacterized seedlings compared with bacterized ones. The seed dry weight and yield for each variety were also significantly higher in bacterized seedlings than in nonbacterized ones. The population of NBRI2650R persisted throughout the growing season of chickpea in the range of 5.4–6.4 log10CFU/g root.Key words: chickpea, competition, rhizosphere, biocontrol, survival.

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Ha M0no)JbIx MaCJIHHaX, BbIPaIUeHHbIX H3 3eJIeHblX YepeHKOB (Ha CTiSqHH Be~TWBHOTO pa3MHO)KeHWII W B OTKPbIToM rpYHW), 6~n o ki30JIWpoBaHO Y e T b l p e BWa I-PM~OB: Macrophomina phaseolina, Nectria haematococca, Armillaria mellea, Corticium roljsii. 06cnenoeaHan MeCTHOCIH W JIa60paTOpHbIe aHWlU3bI nO3BOJIWnW WX YCTaHOBUTb W BbIIIBWTb. Bibliographie Boulila M (1994) Le deptrissement de I'olivier en Tunisie: premiers risultats de recherche et perspectives d'avenir. 72rnes Journies Biologiyues Sociifi Chirnie Biologique. Hammdmet (TN). Boulila M (1997) Contribution i I'itude du phinomkne du diptrissement de I'olivier issu de boutures herbacrtes en Tunisie. Mimoire de DEA d'Ecologie Gherale. Facultt des Sciences, Sfdx (TN). Boulila M, Mahjoub M, Romdhani MS & Ben Othman MN (1993) La maladie du pourridit-agaric observie dans des oliveraies tunisiennes. Bullerirr OEPP/EPPO Bulkfin 23, 447-448.