EpiC– the future of agronomy, is here today.
Plant Growth-Promoting Bacteria (PGPB):
Mechanisms and Applications
- Have the potential to replace many of the chemicals currently used to control diseases in numerous crops.
- Stimulates plant growth through a variety of methods.
Unfortunately, there is likely no one simple best biological nor one best rate or time of application. Despite this lack of perfect knowledge there are still significant benefits that can be realized today.
Given the desire in all areas of agriculture to develop sustainable agricultural practices, many producers are already interested in learning more about these opportunities and using biological crop treatments to improve the economic production of their crops.
Bacteria Concentrations
Of all microscopic life forms in soil including bacteria, fungi, actinomycetes, protozoa, and algae; bacteria are by far the most common. However, the presence of bacterial cells does not insure these cells are culturable and more important the number can vary from 10 9 cells per gram of soil in healthy, productive soils to as low as 10 4 in challenged soils. The concentrations of these bacteria tend to be more active in the rhizosphere or root zone of the plants. The higher concentration is at least partially explained by the increased presence of nutrients including sugars, amino acids, organic acids, and other small molecules from plant root exudates and the symbiotic relationships that exist.
“Increasingly, bacteria that can promote plant growth, that is, PGPB, include those that are free-living, those that form specific symbiotic relationships with plants that can colonize some or a portion of a plant’s interior tissues. PGPB may promote plant growth directly usually by either facilitating resource acquisition or modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogenic agents on plant growth and development, that is, by acting as bio-control bacteria”
Before there will be extensive adaptation of PGPB issues such as how to select the best strains for all the various environmental conditions such as hot, sandy, high pH soil and cool, wet, low pH soils in addition to plant types as diverse as soybeans to alfalfa to corn to lettuce. Still, there are obvious opportunities to benefit from improving the microbial balance of the soil and plants. While it is doubtful that optimum recommendations and placements of these microorganisms is possible today with our limited current knowledge, there is an obvious opportunity to take advantage of some of these benefits.
Previously, many producers and most agronomists have recognized the importance of bacteria and other microorganisms in improving plant health and growth. The direct mechanisms, which are commonly credited with having some benefit include; facilitation of resource acquisition from both organic and inorganic sources. This would include nitrogen fixation and phosphorous solubilization, sequestering micronutrients such as iron and boron etc. Direct mechanisms also exist such as the production of cytokinins and gibberellins in addition to modulation of phytohormone levels impacting the plant’s hormonal balance and in particular the hormonal balance in response to stress.
Now there is an increased interest in indirect mechanisms which PGPB have on plant growth. The benefits of antibiotic and lytic enzymes plus siderophores. These compounds all can have negative impacts on pathogenic bacteria and particularly fungi either by production of enzymes which degrade cell walls of pathogenic fungi or interfering with the uptake and or utilization of micronutrients such as iron by the pathogens. Other proposed indirect modes of action of PGPB include simple competition and induced systemic response, or essentially immunity. Perhaps, the largest benefit of PGPB will be the result of learning more on possible benefits from their ability to produce ethylene and other antifreeze proteins or trehalose which has been identified as an aid in protecting plants from high temperatures and drought.
Conclusion – PGPB have the potential to become an integral component of modern agricultural production. EpiC is one of the best current offerings of a combination of both PGPB and the essential nutrients to stimulate the growth of microbes which benefit the growth of a wide variety of crops.
– For maximum benefits EpiC should be used in combination with other modern agronomy practices recommended by growers’ agronomist.
There are several possible modes of action thru which EpiC improves plant growth and regrowth. First there has been repeated documentation of the beneficial roles that bacteria have on plant growth. For decades the importance of bacterial plant interactions in the rhizosphere have been known and documented. Free living bacteria which are beneficial to plant growth and health are recognized both as Plant Growth Promoting Bacteria as well as Plant Health Promoting Bacteria.
PGPB/PHPB
– synthesize particular compounds beneficial for plants
– facilitate the plants’ the uptake of specific nutrients
– lessen the negative impact from plant diseases
– prevent the deleterious effects of phytopathogenic organisms
– biological control of plant pathogens
– production of plant hormones (auxins, cytokinins, gibberellins, ethylene etc.)
– increased solubilization of minerals which enhance resistance to stress
– improved nitrogen and phosphorus availability and uptake
In addition to the known benefits above more recent work has shown the importance of plants ability to perform rhizophagy. Rhizophagy is a biological process thru which live microbial cells are engulfed by root cells. These cells are then digested and the microbial nutrients then directly available to the plants.
These organic nutrients are the highest quality and most available nutrient forms plants can benefit from.
When plants are grown in environments where there are naturally occurring high levels of elements at toxic levels or the level of these toxic metals and compounds are the result of environmental pollution, PGPB can be of benefit. PGPB modulate the availability of potentially toxic minerals and compounds while improving the balanced uptake/availability of all nutrients.
POSSIBLE MODES OF ACTIONS OF NuCal and Scarecrow
“RHIZODEPOSITS” – polysaccharide mucilages are secreted in the root cap zone. Detached these are metabolically active and form border cells, this physical and biological barrier then interacst with the bacteria affecting everything from sporulation to suppression of plant pathogens.
“BIOLOGICAL BIOCIDIAL ACTION” – selectively protecting plants by displacing pathogens via cpmpetitive exclusion and by producing toxins that kill pathogenic microbes. Especially imnportant maybe the ability of the non-pathogenic bacteria and fungi in EMT products to stimulate an immune response or modulating the plant’s immune system so the plant’s own immunity defenses are more effective against pathogens.
“MYCORRHIZAL NETWORK” – there are symbiotic relationships between root hairs through a mycorrhizal network that allows plants to essentially communicate the presence of disease and or toxins allowing non-affected plants to produce higher levels of defense related enzymes (peroxidase, chitinase, B 1-3 glucanase, lipoxygenase etc.)
“BACILLUS SUBTILIS ANTIMICROBIAL PEPTIDE” – B. subtilis produces a peptide which suppresses toxins at the root surface allowing the B. subtilis to colonize the root zone while also warding off soil borne pathogens. Some of this benefit may be from the B. subtilis also stimulating the plant’s own production of salicylic acid which aids in resisting bacterial diseases.
“DROUGHT TOLERANCE” – it is common knowledge that PGPB stimulate the production of more and longer root hairs. As a result, photosynthesis and biomass synthesis has been shown to increase by as much as 40% under drought condition. Partially, this benefit is attributed to the PGPB’s ability to alleviate salt stress by reducing the production of ethylene in seedling plants. Bacillus subtilis have also been shown shown to regulate stomatal closure through the production of abscisic acid. This same acid has been shown to a benefit when plants are inoculated with B. subtilis, stomatal closure is stimulated and disease levels are reduced.
“MICROBIAL BALANCE” – maintaining a balance of beneficial species of bacteria and microbes optimizes plant health and growth. EMT selectively provides both the beneficial bacteria and fungi along with the organic substrates and compounds to stimulate the growth of the desired bacterial populations.
“VOLATILES AND AIRBORNE CHEMICAL PRODUCTION” – Volatile organic compounds (VOCs) from PGPB’s have been shown to increase crop growth and crop yield. Strains of PGPB release VOCs which trigger plant growth. Specific compounds such as 2,3 butanediol and acetonin are two compounds identified and known to produce increased plant growth.
Scarecrow
A combination of bacteria, fungi, essential trace minerals and organic nutrients designed to maximize soil and plant health by improving nutrient availability and minimizing effects of heat stress, drought and disease.
NuCal
Supplement designed to provide the proper balance of organic nutrition and specialized microorganisms to soils and crops severely challenged by high salt content and stressed by alkalinity and drought.