There is probably only one method to introduce rhizobacteria to plants already planted in pots for an experiment and that is drenching the bacterial suspension near the roots

Hi Konstantinos,

Probably, you could add these bacteria by mixing the inoculum with the water (autoclave and sterilized) you are using to irrigate the plants

I hope the soil is sterilised - we grow the bacteria to be inoculated in sorghum added to LB media so that it is easier to mix with soil before planting crops. Interaction is best in young developing roots - mature plants may not interact at properly.

Dear Martinos,

You have to explore the soil conditions of the pot before inoculation, because you have to set an control for your experiment before going to analyse the effect of rhizobacteria on plants. In the inoculation process you can amend the soil with microbial culture, by maintaining the rhizospheric  count of the bacteria and mix it properly with the soil. 

However it would be better if you set the experiment with initial inoculation during the planting of the experiments.

Good Luck.

Dear Martinos

It is better to inoculate the seed with the target rhizobacteria  inoculant then after planting it is better to inoculate the soil  once with inoculum that contain  million viable cells /ml. 

Before introducing  rhizobacteria  to soil you have to select which kind & functional group your experimental design was plained

There is probably only one method to introduce rhizobacteria to plants already planted in pots for an experiment and that is drenching the bacterial suspension near the roots

I have previously added Rhizobium to seedlings growing in sterilised soil, and have done as Poona suggests. The bacteria were made up into a suspension in either dilute sucrose solution or dilute phosphate buffer then added directly to the base of the plant. This proved effective and plants were found to have produced root nodules at harvest and to fix nitrogen.

I have done as Margaret suggested. First I have grown the bacteria on the apropriate culture medium, and obtained a concentrated suspension of bacterial cells on sterile phosphate buffer. It is important to remove any residues from culture media from the cell suspension beffore applying to the pots. I had ressuspend the bacterial cells twice on phosphate buffer prior to applying to the pots. Before applying it is important to water the pots to create an adequate ambient so that a biofilm directs the bacteria to the roots. If you intend to introduce more than one bacterial species, it will be important to determine the correct proportion of each will be more effective, sometimes the proportion may be 1:100 or less.

I was interested in applying P-solubilising bacteria to non-sterile soil, so I grew the strains in suitable media then inoculated sterile peat in plastic packets, as for rhizobium inoculum in Australia. The seeds were surface-sterilised, then dipped in seed-pelleting adhesive followed by the single PGPR strain of interest, before planting.

In non sterilized soil the most effective methods is to inoculate sterilized seeds or seeds germinated in sterilized conditions and then planted. Moreover rhizobia  are different from other PGPRs because rhizobia enter roots. Most of other PGPRs establish in the rhizosphere where other soil-rhizosphere  microbial population already grow in non-sterile conditions and for these reasons the establishment of inocula is much more difficult

Yes, I agree drenching the soil near plant with culture will help

of course you can

first centrifuge the bacteria suspension, remove supernatant and resuspend it in water (with 8 gram per liter NaCl). adjust bacteria population to 10 power 9 or OD: 0.5

and irrigate your pots with suspension like your normal irrigation. you can add 0.1 percent of CMC for better suspension viscosity