Plant Growth Promoting Bacteria, or PGPB, are a major factor in determining plant health, plant productivity and overall soil fertility.
Definition of PGPB
Plant growth promoting bacteria, present in the rhizosphere, are beneficial soil bacteria that enhance plant growth and reduce the abiotic stresses through a variety of mechanisms. Since these beneficial bacteria are found in the rhizosphere, you will sometimes see the term PGPR, plant growth promoting rhizobacteria, used.
Several plant microbe interactions are generally classified as PGPB including:
- Phosphate solubilization
- Biological nitrogen fixation
- The production of phytohormones
- ACC deaminase activity
- The production of siderophores
Benefits of PGPB
Plant growth promoting bacteria provides several specific benefits to the plant including; increased agronomic activity, reduced overall production costs, and reduced environmental pollution.
Increased agronomic activity is the goal of every farmer, both commercial and home gardener. The use of PGBR increases root size and root strength in plants and in turn, these healthier roots help produce stronger, more productive plants.
The reduction in environmental pollution is achieved because less traditional fertilizers (NPK) are generally needed when sufficient amounts of plant growth promoting bacteria are added. This means that the fertilizers are used more efficiently and this more efficient usage reduces costs and fertilizer runoff issues. Less use of NPK means less fertilizers wash away and since fertilizer runoff is an environmental issue, use of PGPB helps reduce this problem.
For beneficial bacteria to be effective, several factors must be considered:
- Overall soil condition, including soil pH, water, minerals, soil porosity
- Extent of bacterial colonization of the root zone
- Amount and types of plant exudates
The Future of Beneficial Microbes
Plant growth promoting bacteria have only recently become of interest to scientists and farmers. Over the next decade, more research will be done in this promising area.
Bill Baugh is a product manager for Custom Biologicals, Inc. a manufacturer and distributor of innovative microbial products. You can visit their website at Living-Soils.com.