The role of root rot is massive in modern soil borne agriculture.

Beside inhibiting root rot fungi and bacteria the seeds and seedlings with a positive microbiome favor plant yield and nutrition and lower need for toxic inputs.

A bacteria of the Pseudomonas genera can inhibit take all disease of Wheat a major world food staple.

Ideally the controls of this type are selected to be applied in treated seed available to farmers and with a vision toward there persistence in the rhizosphere.

Plants defend themselves against pathogens by multiple well-described mechanisms such as innate (non-host) immunity, localized race-specific resistance, and systemic resistance. Equally important are microbial-based mechanisms of root defense against soilborne pathogens that are modulated by the plant through root exudates, leading to the stimulation and support of populations of antagonistic rhizosphere microorganisms including Pseudomonas spp.

This mechanism often constitutes the first line of defense against root-infecting soilborne pathogens. Disease-suppressive soils provide some of the best examples of indigenous microorganisms protecting plant roots against soilborne pathogens. Suppressive soils are known for many pathogens, occur worldwide, and provide highly effective and sustainable control of certain diseases with minimal off-farm inputs. Long-standing suppression is naturally associated with soil and is of unknown origin, whereas induced suppression develops as a result of a cropping practice, most commonly crop monoculture.

One of the best known examples of natural soil suppressiveness is take-all decline (TAD), which develops during wheat or barley monoculture following an outbreak of take-all. The basis of TAD is the build-up of populations of fluorescent Pseudomonas spp. producing 2,4-DAPG and accumulation of the antibiotic in the rhizosphere. The take-all pathogen G. graminis var. tritici is highly sensitive to this antibiotic. Studies of the interactions among wheat roots, the take-all pathogen, 2,4-DAPG producers and the rhizosphere microbiome are providing fundamental new insights at the molecular level as to how indigenous microorganisms “hear the cry for help” and “come to the rescue” when wheat is attacked by soilborne pathogens.

Dr Paul Reed Hepperly thank you for your contribution to the discussion

Plant growth-promoting rhizobacteria (PGPR) are a diverse group of beneficial bacteria that colonize the rhizosphere, the region of soil around plant roots. PGPR promote plant growth and health through a variety of mechanisms, including:

• Nutrient solubilization: PGPR can solubilize insoluble nutrients, such as phosphorus and iron, making them more available to plants.
• Phytohormone production: PGPR can produce phytohormones, such as auxin and cytokinin, which stimulate plant growth and development.
• Nitrogen fixation: Some PGPR can fix atmospheric nitrogen, making it available to plants in the form of ammonium.
• Biocontrol of plant pathogens: PGPR can compete with plant pathogens for nutrients and space, and some produce antibiotics or other compounds that inhibit pathogen growth.
• Abiotic stress tolerance: PGPR can help plants to tolerate abiotic stresses, such as drought, salinity, and heavy metal toxicity.

PGPR can play an important role in improving crop productivity in sustainable agriculture by reducing the need for synthetic fertilizers and pesticides. They can also help to improve soil health and resilience.

Here are some specific examples of how PGPR have been used to improve crop productivity:

• In India, PGPR have been used to increase rice yields by up to 20%.
• In China, PGPR have been used to increase wheat yields by up to 15%.
• In Brazil, PGPR have been used to increase soybean yields by up to 10%.

PGPR are a promising technology for improving crop productivity in a sustainable way. They are relatively inexpensive and easy to use, and they have a wide range of benefits for plants and soil.

In addition to the above, PGPR can also help to improve crop productivity by:

• Increasing root growth and development
• Enhancing nutrient uptake efficiency
• Inducing systemic resistance to pests and diseases
• Reducing the need for irrigation
• Improving soil structure and aeration

Overall, PGPR are a valuable tool for sustainable agriculture, and they have the potential to play a significant role in meeting the world's growing food demand.

Dr Murtadha Shukur thank you for your contribution to the discussion

PGPMs enhance the growth of plants by reducing the ethylene production through secretion of ACC (1-aminocyclopropane-1-carboxylic acid) deaminase enzymes and Pseudomonas, Serratia, and Bacillus enhance the growth of plants via secretion of ACC deaminase enzymes. Plant growth-promoting rhizobacteria are microbes associated with plant roots that promote plant growth by (1) providing enhanced mineral nutrition, (2) producing plant hormones or other molecules that stimulate plant growth and prime plant defenses against biotic and abiotic stresses, or (3) protecting plants againstdiseases and pests. Rhizobacteria also decrease the fertilizer input and promote plant growth by solubilizing the fixed nutrients and by providing the hormones and other growth-promoting substances. The plant growth-promoting rhizobacteria (or PGPR) are the beneficial microorganism that colonizes rhizosphere and help in promoting plant growth, protecting from biotic and abiotic stresses, and significantly increasing soil fertility. The plant growth-promoting bacteria (PGPB) belong to a beneficial and heterogeneous group of microorganisms that can be found in the rhizosphere, on the root surface or associated to it, and are capable of enhancing the growth of plants and protecting them from disease and abiotic stresses. Some rhizobacteria are able to produce phytohormones, including cytokinins, auxins, gibberellins, ethylene, and abscisic acid (ABA), which play a role in different growth processes in plants, including cell multiplication, which results in increased cell and root expansion. The rhizosphere harbors diverse microbial groups that perform various functions and exert numerous effects on plant growth. They are involved in nutrient cycling, protecting from phytopathogens as well as under biotic and abiotic stress conditions, and some may act as plant pathogens.

The role of bacterial population is important in plant health and disease suppression. When bacterial can get to 10 to ninth power plant health and supporession can be seen in compost teas and below that level performance is compromised.

In the soil the disease condition is most problematic at low population levels and the vast majority of natural microbial are beneficial and or neutral and not pathogenic.

The increase of microbe soil population is largely a funition of increasing soil organic matter. When soil organic matter is 5% or more there is much less issues with root rot complex.

Currently the soils cultivated are mostly less than 2% soil organic matter.

As our question how have highlighted the role of hormones to stimulating rooting which are of microbial origin. Add the solubulization of macro meso and micronutrients.

About 2 thirds of our soils are not optimized for pH which works to give the proper microbial potential.

Dr Paul Reed Hepperly thank you for your contribution to the discussion