1. Influence of membrane effectors on mixed biocoenosis
Symbiosis between microorganisms and higher organisms is essential for any well-functioning system. An example of this is the intestinal flora. But not only the intestine is colonized by various bacteria. The entire microbiome of a human weighs about one to two kilograms and makes up 50% of the cells in the human body. If the microbiome gets out of balance, a variety of diseases, such as depression or adipositas are the result.
Not only humans are dependent on a functioning symbiosis with bacteria. Plants also live in complex communities with bacteria and fungi. These microbial mixed biocoils are essential for plant growth. The various species are in various relationships with each other, which are responsible for the individual balance of each community. (Illustration 1).
Genau an diesem Punkt setzen unsere Biostimulatoren an. Sie überführen Mischbiozösen gezielt in die gewünschte Zusammensetzung, indem sie das Wachstum einzelner Spezies fördern.
2. Change in Nutrient Dynamics through Biostimulants
Natural topsoils (mother soils) contain a very large number of bacteria, fungi and ray fungi (microorganisms), in addition to unicellular organisms, nematodes, springtails, insects, insect larvae, snails and earthworms (up to 4,000 kg / ha) for the metabolism in soils of considerable Meaning are.
The food of the microorganisms is the so-called nutrient humus, which is produced by microbial activity from organic masses. Microorganisms play an important role in soils through the excretion of mucilage. Mucilagins cause the soil to crumble (Bodengare). At the same time, mucilages buffer acids and alkalis in the soil. In very cohesive soils, the gare ensures that the soil no longer breaks when it dries out in floes and under pressure elastically returns to its original shape, so that compaction can be avoided. In very loose, sandy soils, the water storage capacity increases and mucilage buffer the effect of pollutants and salts.
In crumbly soils there is a favorable ratio of coarse and fine pores. The released carbon dioxide during the respiration of microorganisms and roots can in such be removed quickly and oxygen can penetrate. Central pores store water at short notice and at the same time serve as drains, while fine pores protect the water from seepage for weeks and months due to capillary forces. The proportion of dead water (ultrafine pores with non-plant-available water, especially in clay soils) is reduced. Good ventilation also prevents water supersaturation and thus too slow warming in the spring.
The following improvements can be achieved for the individual types of soil:
- Sandy soil:
Increase of water and nutrient storage capacity, reduction of humus consumption, better buffering, better salt tolerance.
- clay soils:
Increased water permeability, lower nutrient fixation, better ventilation, faster warming of the soil, no organic material migration due to lack of oxygen, better machinability.
In both cases, the water supply is improved. Since soils in good condition are ideal for a minimal, superficial tillage, there are also economic advantages.
3. Effect of Biostimulants on Plant Nutrition
Plant roots are covered with a symbiotic layer of rhizosphere microorganisms. These microorganisms thrive on rooting and produce phytohormones (gibberins, auxins) that promote root growth – a complete loop (Figure 2).
Under natural conditions, in contrast to culture conditions, there is always a lack of nutrients in the soil. Bacteria are able to release nutrients from soil particles. If nutrients are not needed, for example in a growth stop, the root does not secrete and thus does not promote the bacteria. On the other hand, increased leaf growth means a higher rate of photosynthesis and, as a result, higher secretion of the root. So microorganisms are promoted and mobilize nutrients from the soil.
Nutrients are present in the soil in two important forms:
- Mobile form:
as soluble salts, which can be taken up in this form (and almost only in this form) from the root and
- Immobile Form:
bound to the humus substance or in inorganic form. The amount of nutrients bound to humus depends on the humus content. The release from the immobile form, but also the binding in immobile form are for the most part effected by microorganisms.
The supply of nutrients to the plant takes place in practice to a considerable extent by mobilizing specified nutrients from the soil components. Soil bacteria play a major role. Nitrogen, phosphate and potash are released in particular from organic bonding. The bacterial activity is temperature-dependent and thus adapted to the seasonal nutrient requirements. In times of highest demand but the supply of the plants from the organic storage form is only possible if very many bacteria are present.
By biostimulation using membrane effectors, it is possible to increase the bacterial biomass of the root zone and increase root growth. More roots also means more organic matter in the soil, without it coming to the exclusion of air. In the process, bacteria already colonize the seed before the first root has formed. (Figure 2).
4. Mobilization and immobilization of nutrients in the soil
In the following, nitrogen, the most mobile element, will be considered:
- Mobile form:
Nitrogen is present in the soil solution as nitrate and ammonium. The (positively charged) ammonium form is bound to (negatively charged) soil particles via ionic bonding. The nitrate form is mainly absorbed by the plant. This mobile nitrate form is subject to leaching into groundwater. If enough organic matter and little oxygen are present, nitrate is also denitrified (converted into gaseous nitrogen and partly into nitrous oxide).
- Immobile form:
Bound by organic matter (humus), nitrogen is present in organic form. You can assume the following optimal quantities:
If the content of nitrogen is higher, the excess should be gradually mobilized.
When mobilized by bacteria (whose activity is temperature-dependent), there may be a supply gap at low soil temperatures. In this case, it is necessary to provide a small amount of quickly available fertilizer.
Biostimulants as soil adjuvants:
By increasing the microbial activity in the soil it is achieved that in the mobile phase there is very little nitrogen. After fertilization, the immobile reserve is replenished. The nitrogen losses due to leaching and denitrification only occur from the mobile phase. Due to the high microbial activity, the mobile phase is quickly replenished as required by the plant, but the supply of the plant is still guaranteed.
High nitrate levels in the soil also inhibit nitrate uptake in the plant. Nitrate must be converted into nitrate via nitrite form by nitrate reductase. This acts as an alkalizer in the rhizosphere, which inhibits sucrose transport in the plant, which in turn reduces nitrate utilization. Nevertheless, to achieve a good nitrate uptake, the plant must be literally flooded with nitrate. This circulus vitiosus is overcome by biostimulators. The content of mobile nitrogen remains low, the inhibition of intake is omitted. At the same time, the bacteria quickly supply sufficient nitrogen from the immobile form.
5. Principle of resistance induction
In warm-blooded animals, an infectious disease that has survived can lead to immunity to the same pathogens. The same is also known by plants. However, in contrast to warm-blooded animals, the immune response is far from being specific, and moreover, not the whole plant is protected, but only the affected organ (eg the leaf). As with warm-blooded animals, inoculation (vaccination) with virulent or avirulent pathogens (saprophytic bacteria or phyllosphaeric fungi, extracts of bacteria and fungal spores) or infection with host RNA or viral protein can also occur in the plant. However, the acquired resistance not only acts against these pathogens, but also unspecifically against other bacteria, fungi, viruses or nematodes. It can be local or (rarely) systemic.
Between inoculation and resistance training take 2-14 days. The induced resistance persists between 20 days (tobacco mosaic virus) and a full growing season, but usually 6-8 weeks.
A particular effect is possessed by certain oligosaccharides. When plant tissue is irritated or destroyed, the polypeptide pro-systemin is released, which converts to systemin by proteolysis. The same effect of natural oligosaccharides on the leaf surface. Systemin attaches to a receptor in the plasmalemma, activating a lipase that releases linoleic acid from the membrane. Together with a lipoxygenase (LOX), jasmonic acid forms over several steps. Jasmonic acid activates as a signal substance a gene encoding a proteinase inhibitor. In the digestive tract of insects, this proteinase inhibitor prevents the absorption of protein. The insects migrate or starve to death.
Lipoxygenase in combination with peroxygenase and hydroxylation forms 9.10.18-trihydroxystearic acid, from which wax builds up on the leaf surface. A thicker wax layer protects the plant against the ingress of fungal hyphae and insects. It also reduces (non-stomatal) perspiration and protects the leaf from airborne contaminants such as nitrogen oxides and ozone. Other oligouronides activate elicitors, such as phenylalanine ammonium lyase (PAL), which activate genes encoding antimicrobial phytoalexins.
It is still unknown why certain oligouronides cause higher chlorophyll production in plants.