In this regards phosphate-solubilizing microorganisms (PSM) have been seen as best eco-friendly means for P nutrition of crop. Although. Phosphate-solubilizing bacteria and fungi play an important role in P bioavailability and can be used to increase PUE (Bolan et al., ). The bacteria and fungi. Phosphate-solubilizing bacteria play a vital role in P solubilization by producing organic acids. Additionally, soils contain low molecular weight.


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The term P fixation is used to describe reactions that remove available phosphate from the soil solution into the soil solid phase Barber The soils that exhibit highest P fixation capacity occupy 1, million hectares ha in the tropics Sanchez and Logan It is for this reason that soil P becomes fixed and available P levels have to be supplemented phosphate solubilizing bacteria most agricultural soils by adding chemical P fertilizers, which not only represent a major cost of agricultural production but also impose adverse environmental phosphate solubilizing bacteria on overall soil health and degradation of terrestrial, freshwater and marine resources Tilman et al.

phosphate solubilizing bacteria

Phosphate solubilizing bacteria and their role in plant growth promotion.

Thus, increased P levels have been identified phosphate solubilizing bacteria a main factor for eutrophication of surface waters that may lead to algal blooms Schindler et al. The repeated and injudicious applications of chemical P fertilizers, leads to the loss of soil fertility Gyaneshwar et al.

The long-term effect of different phosphate solubilizing bacteria of phosphate fertilizers on microbial activities includes inhibition of substrate-induced respiration by streptomycin sulphate fungal activity and actidione bacterial activity and microbial biomass carbon C Bolan et al.

It has been suggested that the accumulated P in agricultural soils would be sufficient to sustain maximum crop yields worldwide for about years if it were available Khan et al.


Furthermore P is a finite resource and based on its phosphate solubilizing bacteria rate of use, phosphate solubilizing bacteria has been estimated that the worlds known reserves of high quality rock P may be depleted within the current century Cordell et al.

Beyond this time the production of P based fertilizers will require the processing of lower grade rock at significantly higher cost Isherwood The realization of all these potential problems associated with chemical P fertilizers together with the enormous cost involved in their manufacture, has led to the search for environmental compatible and economically feasible alternative strategies for improving crop production in low or P-deficient soils Zaidi et al.

The use of microbial inoculants biofertilisers possesing P-solubilizing activities phosphate solubilizing bacteria agricultural soils is considered as an environmental-friendly alternative to further applications of chemical based P fertilizers.

Constraints in using phosphate fertilizers There is global concern about the energy and costs involved in mining the rock phosphate and its transport from manufacturing sites to farm crop fields.


Mining phosphate minerals and spreading P fertilizers over the landscape phosphate solubilizing bacteria neither eco-friendly, economically feasible nor it is sustainable and it poses following constraints i emission of the fluorine as the highly volatile and poisonous HF gas, ii disposal of gypsum and iii accumulation of Cd and other heavy metals in soil and possibly crops as a result of repetitive use of P fertilizers.

In India, deposits of sufficiently enriched phosphatic rocks are limited and hence it imports 2 million tons of rock phosphate annually. Intensive cropping phosphate solubilizing bacteria during this green and white revolution has also resulted in widespread deficiency of phosphorus.

Although various amendments are available for management of P in different soil, all are costlier and practically difficult.

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Thus, even if the total soil P is high and also if P fertilizers are applied regularly, pH dependent chemical fixation determines the quantity of available P. The holistic P management involves a series of strategies involving manipulation of soil and rhizosphere processes, development of P efficient crops and improving P recycling phosphate solubilizing bacteria.

Total bacterial populations, P solubilization, soil pH, root morphology, and agronomic parameters phosphate solubilizing bacteria recorded after 40 days of growth.

Seed Surface Sterilization, Inoculation, and Growth of Rice Seedlings The surface sterilized seven days phosphate solubilizing bacteria seedlings were transplanted into pots containing sterilized soil ?

Plants were grown for 40 days in a growth chamber with 12?


PSB16 were used as inoculum in each bacterial treatment. Determination of Bacterial Population, Plant Biomass, and Plant Tissue P The total bacterial phosphate solubilizing bacteria was determined from rhizosphere, nonrhizosphere, and endosphere of aerobic rice plants.

After harvest, soil available P was determined using Bray 2 [ 14 ] and total plant tissue P was analyzed by the wet digestion method [ 15 ]. Determination of Root Development The root length cmtotal surface phosphate solubilizing bacteriaand root volume cm3 were quantified using a scanner ExpressionEpson equipped with a 2?

Data Analysis The experiment was conducted with the three factors in four replicates in a completely randomized design.

Phosphate solubilizing bacteria and their role in plant growth promotion.

Data obtained were statistically analyzed using the SAS software program Version phosphate solubilizing bacteria. Significantly high amount of solubilized P Effect of a oxalic acid b malic acid on P solubilization. Bars indicate standard error.