We continue from our blog talking about the use of microorganisms to improve the vital functions of plants. In this case we specifically deal with the usefulness of probiotics for plants, bioformulations that, depending on their typology, have one or another function and utility.
For our microbiology team, a wide range of new possibilities has been opening up in recent times through the use of microorganisms. But let’s start by remembering what probiotics are according to the European Biostimulant Industry Council (EBIC). According to this organism, they are substances and/or microorganisms that, applied to plants or to the rhizosphere, stimulate natural processes, improving/benefiting the absorption of nutrients, nutritional efficiency, tolerance to abiotic stress and crop quality.
The use of probiotics is supported by scientific studies and organizations such as the FAO, since it provides benefits such as greater plant growth, more defenses against pathogens, better solubilization of minerals or greater fixation of atmospheric nitrogen.
Plant probiotics are also called Plant Growth Promoting Microorganisms (PGPM). And to be considered as such they must:
- Do not invade the internal tissues of the plant.
- Being able to colonize the root surface.
- Reach a high microbial concentration in the rhizosphere.
- Do not affect humans or other beneficial microorganisms.
These microorganisms, usually bacteria and fungi naturally present in the soil within the root, help to produce natural phytohormones and improve nutrient uptake.
- The most common probiotic bacteria in soil are Bacillus, Pseudomonas, Azotobacter, Serratia, and Azospirillum.
- And the most common fungi are Trichodermas and mycorrhizal fungi, Gigaspora and Rhizophagus.
TYPES OF PROBIOTICS AND FUNCTIONS
Biofertilizing probiotics
It is one of the best features of using beneficial microorganisms for plants and trees. Reasons?👇
- They improve the ability of the plant to capture nutrients and, therefore, achieve greater growth and higher crop productivity.
- They have a lower environmental and economic impact than other inputs.
- Being zero waste products, they generate healthy food for people. The probiotics applied to our crops improve the nutritional properties of vegetables and fruits. For example, better levels of carotenoids or secondary metabolites such as flavonoids and other phenolic compounds with antioxidant function have been perceived.
Among the qualities that make probiotics magnificent biofertilizers are⬇️
Certain microorganisms facilitate the assimilation of nitrogen (N₂), by converting it into a metabolically available molecule. Probiotics fix it in more assimilable forms for the plant.
Some soil bacteria -such as Azotobacter, Pseudomonas y Rhizobium– are capable of mobilizing phosphorus, helping plants to absorb it.
Bacteria of the genera Chryseobacterium and Pseudomonas have the capacity to produce siderophos secreted by fungi and bacteria can supply iron to the plant, favoring both growth and germination of the plant.
Some microorganisms also contribute to plant growth, cell division, or root extension by producing phytohormones such as auxins or gibberellins.
Biocontrol probiotics
Microorganisms also exert a biocontrol function, by protecting the plant in a non-specific way from the effects of pathogens and abiotic stress.
As? Through mechanisms such as👇
- The competition. Microorganisms such as the bacterium Pseudomonas fluorescens prevent the proliferation of phytopathogens in the rhizosphere through competition for nutrients.
- Induced Systemic Resistance. Probiotics can favor what is called ISR, that is, mechanisms of resistance to phytopathogens and insects dependent on plant hormones.
Probiotics with phytosanitary functions
Well indeed. Microorganisms also secrete substances that help control pests and diseases in crops, such as👇
- Hydrolytic enzymes, with which plants are able to deal with certain fungal infections.
- Hydrogen cyanide (HCN), a secondary metabolite produced by some rhizobacteria to prevent weed growth. It also has antifungal qualities.
- Antibiotics. For example, pseudomonas bacteria are capable of producing pseudomonic acid (which inhibits the synthesis of bacterial proteins) and those of the genus bacillus generate subtilin (which acts on the wall of fungi).
For all these reasons, for the MAFA team, research and study is a priority, to formulate probiotics that:
- Facilitate the growth of plant growth promoting microorganisms (PGPM).
- Increase microbial viability in good physiological conditions.
- They have good adhesion to the plant structure.
- Have a high pH buffering capacity.
- And, of course, they do not generate waste. That is, they conform to zero residue agriculture.
