hmm not really death but decrease the growth

Do you have reference to this?

Specifically about PGPR

Azotobacter sp.

Azospirillium sp.

Pseudomonas sp.

Bacillus sp.

Aspergillus sp.

Christa , if i have understood your question correctly , you  mean , why to use chemical fertilizers over  PGPRS ?. Wonderful , we debated this issue earlier also. these PGPRs also need some starter nutrients  , may come either through inorganic sources or through organic sources . However , most important is to maintain the microbial load of the soil in an acceptable quantity , so that supply pool of nutrients in soil is maintained at an intensity to be able to maintain the good  growth round the season of a given crop.   Hope , you find answer satisfying...

Christa ,

i want to know wether do you have any scientfic reference of PGPR which causing decrease in plant growth.

generally PGPR always act as plant growth promoters, but debate is on wether they perform in natural condition or not

up to my knowledge, overuse of chemical fertlizer can cause death of plant but use of PGPR can not. PGPR can increase growth of crop plant or have no effect on plant, depending on the conditions

Question is , how to define over-use of chemical fertilizers , unless  supported with decline in productivity . As long as , application of chemical fertilizers is balanced , soil biological properties will not decline . We should also keep in mind , microbial inoculation alone would not be in a position to replace the use of chemical fertilizers. But , while practicing application of  any  fertilization source  , we need to keep a vigilant eye on soil microbial diversity ...

Sir, from over use I mean over dose. For eg in case of boron or even very high dose of urea applied in a pot can damage the plant

Agree with anup sir

Dear RG colleagues, we should also keep in mind that the excessive use of chemical fertilizers can as well suppress/limit the activity and functions of PGPR (introduced or native). There is a need to strike a balance in the application of both for improved crop productivity.

Thank you very much sir. Do you have a journal? I need it

Dear Christa, please visit my profile and help yourself with the few articles available there. I hope i have helped in my own little way.

Thank you very much sir

Best Regards Christa Utami

In order to clarify your problem, the efficiency of plant growth promoting microorganisms (PGRP), as well as the ionic species of the essential elements present and available in this order of soil (physicochemical and soil characteristics) should have been taken into account to avoid Immolization by PGRP as well as the formation of insoluble compounds between reactive mineral species, it should be taken into account if UREA was used that is not recommended in roses because of the formation of BIURET that under high temperature conditions is highly toxic and one of The most important things is that the root system of the rose is superficial and any alteration in the rhizosphere has direct effects on the physiology of the plant since the rose is a crop susceptible to changes in electrical conductivity in soil solution by This is handled at

Thank you very much. How about in chrysanthemum?

Good point Christa . here is some work for your reference please, hope you like these inputs...

Pseudomonas fluorescens as plant growth promoting Rhizo-Bacteria and biological control agents for white rust disease in chrysanthemum

Abstract: The use of plant growth promoting rhizobacteria (PGPR) to control disastrous diseases in many crops has been considered important recently. The research was conducted to evaluate several bacterial strains to control white rust in chrysanthemum. The research consisted of two chronological experiments, in vitro and in vivo testing of bacterial isolate against the disease. 16 bacteria isolates were collected, purified and applied on the rust-infected leaf. Three isolates showed more effective in suppressing white rust during in vitro testing and further  identification confirmed these strains, Pf Kr 2, Pf Smd 2 and Pf Ktl were grouped into P. flourescens. In vivo testing of the Pf isolates also revealed consistent performances of these three Pf isolates in retarding the growth of fungal Puccinia horiana and even more effective than Azotobacter sp. and Azospirilium sp. The production of ethylene on the leaf was coincidence with the slower development and lower disease intensity on the treated plants. Among the three strains, Pf Kr 2 showed stronger suppression to the disease. Further investigations are needed to further elucidate the existence of specific interrelation between Pf strains and plant genotypes or cultivars. Prior to a selection of good bacterial inoculants, it is recommended to select cultivars that benefit from association with these bacteria.Source ; Int. J. Agr. Agri. Res. 8(4), 22-34, April 2016.

Effects of some plant growth promoting rhizobacteria (PGPR) strains on growth and flowering of chrysanthemum

Abstract:The present investigation was conducted in the screen-house of the Department of Horticulture, College of Agriculture,CCS Haryana Agricultural University, Hisar during the two successive seasons of 2011-12 and 2012-13 to investigate the potential effect of different strains of Bacillus and Pseudomonas on growth and flowering of chrysanthemum. The obtained results revealed that the inoculation of plants with strains of biofertilizers significantly improved the growth and flowering parameters. The maximum plant spread and fresh weight of plant were recorded in plants inoculated with PS2 strain of Pseudomonas (CPA152) and BS3 strain of Bacillus (SB127) in both the years. The dryweight of plant was noticed maximum with PS3 strain of Pseudomonas (P20) and BS2 strain of Bacillus (SB155) in first year and PS2 strain of Pseudomonas (CPA152) and BS3 strain of Bacillus (SB127) in second year. The maximum number of buds/plant was recorded with inoculation of PS3 (P20) and PS2 strains (CPA152) of Pseudomonas, whereas, among Bacillus strains, BS3 (SB127) was recorded best in both the years. The minimum number of days to  first flowering as well as longest flowering duration was recorded with application of PS2 strain of Pseudomonas (CPA152) in both the years, and among Bacillus strains, BS3 (SB127) and BS2 strain (SB155) were found best in the year 2011-12 and 2012-13, respectively. The maximum flower size was noticed with PS3 strain of Pseudomonas (P20) in first year whereas, in second year the response of Pseudomonas strains was found non-significant. AmongBacillus strains, the plants inoculated with BS3 (SB127) recorded maximum flower size. Flower stalk length was significantly influenced by different strains of Pseudomonas and Bacillus. The longest flower stalk was recorded in plants inoculated with PS3 (P20) and PS2 (CPA152) strains of Pseudomonas in the year 2011-12 and 2012-13, respectively. The plants inoculated with BS3 strain of Bacillus (SB127) recorded maximum stalk length in the years. Maximum number of flowers/plant, fresh and dry weight of flower and flower yield/plant were recorded in plants inoculated with PS2 strains of Pseudomonas (CPA152) and BS3 strains of Bacillus (SB127). The number of suckers  plant-1 was noticed maximum with PS3 strains of Pseudomonas (P20) and BS3 strains of Bacillus (SB127) in both the years.Source ; J.Crop and Weed 12(1)..

Thank you very much sir

Here is a PDF of very good review articles , Christa, hope you like it ....

Thank you very much

Another very good review entitled Microbial Inoculants for Soil Quality and Plant Health has come out  in  Volume 22 of the series Sustainable Agriculture Reviews pp 281-307 ( Dated January 19,2017). The abstract is reproduced here :

Agriculture is the major economic activity of most developing countries engaging more than 50 % of the population. Low world crop productivity due to low soil moisture, low nutrient capital, erosion risk, low pH, high phosphorus fixation, low levels of soil organic matter, aluminum toxicity pest and diseases, weeds and loss of soil biodiversity has induced the green revolution agriculture which involves high yielding varieties and agrochemicals. The continuous use of fertilizers, pesticides and herbicides has led to low agricultural productivity, low soil fertility, unfavourable economic returns, food poisoning, soil damage loss of biodiversity and serious environmental hazards. Microbial inoculants possess the capacity to enhance nutrient availability, uptake, and support the health of soil and plants to promote sustainable yield and has therefore gained attention of many agriculturist and researchers.

We review the ability of soil through the use of microbial inoculants to supply nitrogen, phosphorus and potassium to crop plants and enhance structural stability. Microbial inoculants such as rhizobium, plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi can be used as biofertilzer to improve soil nitrogen, phosphorus and potassium availability and uptake. Both bacteria and fungi inoculants show potential for use in soil aggregate formation and stabilization and hence, soil structure enhancement. The ability of microbial inoculants to ameliorate plant stress as a result of drought, soil contamination and salinity are also highlighted. The most commonly used microorganisms as biofertilizers, biocontrol and bioremediators include Bacillus spp, Pseudomonas spp, Streptomyces spp Trichoderma spp and Mycorrhizas. Microbial inoculants function through various mechanisms such as production of plant hormones, expansion and elongation of the root system, eliciting induced systemic resistance or systemic acquired resistance, production of lytic enzyme and antibiotic 4-hydroxyphenylactic acid, and production of 1-aminocyclopropane-1-carboxylate-deaminase (ACC-deaminase) in plants rhizosphere. These strategies are safe and sustainable in the long run. The use of appropriate carrier material determines the success of microbial inoculation techniques. Microbial inoculants could either be applied directly to the soil or as seed dressing. The fate of microbial inoculants under field application depends largely on both biotic and abiotic factors. The application of some microbial inoculants could cause a change (which could be a decrease or an increase) in the equilibrium of soil microbial communities while some produce no effect at all.

Thank you very much sir for your help

Christa , here the PDF as desired by you...Hope , you like it...All the best

Very interesting and helpful findings Anoop sir

Thanks Asif...

Here is another very interesting work..from our desk...entitled SUBSTRATE DYNAMICS : DEVELOPMENTS AND ISSUES...

Rhizosphere modification through root exudation is an important attribute that regulates not only the availability of nutrients in soil, but also their acquisition by plants, besides soil microbial composition. Limited studies on multiinoculation

loaded substrate dynamics with respect to rhizosphere physico-chemical and biological transformations have displayed some promising results in variety of crops. But, long term studies on sustainable impact of substrate on production as well as quality are still in the pipeline. A major breakthrough of late has emerged in this context , is the rhizosphere specific microbial consortium having multiple microbes capable of performing diverse functions. Such microbial consortium needs to be tailored as per crop specific demand so that substrate dynamics becomes more crop responsive with an additional lasting effect on soil biological health.  PDF  ENCLOSED FOR FURTHER READING...

Thank you very much Mr. Anoop

Christa, another very good review...

Abstract : Phosphorus is one of the important primary plant nutrients required by the plant for sustaining long term performance. Trichoderma and Pseudomonas are premier microbes having known for their dynamism in phosphate solubilisation. An incisive analysis of the work done on mechanistic differences in phosphate solubilization by these two microbes showed almost the same mechanisms, though; one is fungus, while another is bacteria. Both besides being good colonizers, are capable of competing under nutrient deficient medium. The solubilization of phosphate is accomplished through number of processes viz., producing chelating compounds like siderophores as chelating agent, secondary metabolites (antibiotics formation), organic acids production and secretion of growth regulators predominantly indole acetic acid.

  Source : Annals of Plant and Soil Research 17(3): 227-232 (2015

Ok sir. Thank you very much