Bacillus subtilis has significant antibacterial activity and strong stress resistance.
Bacillus subtilis widely exists in nature. It is not only active in the external environment such as soil, plant rhizosphere and body surface, but also a common endophytic bacterium in plants. It is non-toxic and harmless to humans and animals, does not pollute the environment, and has significant antibacterial activity and strong stress resistance. Bacillus subtilis has the advantages of fast growth, simple nutrition, heat-resistant and stress resistant spores, and can be made into various dosage forms; Mixed with chemical pesticides without inactivation, convenient application and long storage period. Bacillus subtilis is mainly used to regulate soil, spray, root, seed dressing and seed coating.
The effect of Bacillus subtilis on plants is mainly reflected in the following aspects:
1. Competition between nutrition and spatial loci
The competitive effects of Bacillus subtilis mainly include nutritional competition and spatial site competition. It can reproduce and colonize rapidly and massively in plant rhizosphere, body surface, body and soil, effectively repel, prevent and interfere with the colonization and infection of plant pathogenic microorganisms on plants, so as to achieve the effect of bacteriostasis and disease prevention.
Significance of competitive effect: after seed dressing or root irrigation, Bacillus subtilis can be transmitted to the aboveground part through plant conduit to colonize and reproduce on the surface of crop roots, roots, stems, leaves and other parts, so as to protect crop roots from bacterial infection and inhibit the spread of pathogens in production objects, so as to achieve disease prevention.
2. Produce bacteriostatic substances
Bacillus subtilis can produce a variety of substances with bacteriostatic and bacteriolytic effects in the growth process, such as subtilisin, organic acid, antibacterial protein and so on. These substances can inhibit the growth and reproduction of pathogenic bacteria, even destroy the bacterial structure and kill pathogenic bacteria. Therefore, Bacillus subtilis has a good control effect on continuous cropping disease, root rot, gray mold and other diseases. The bacteriolytic effect of Bacillus subtilis is mainly manifested in that it adsorbs on the mycelium of pathogenic bacteria and grows with the growth of mycelium, and then produces bacteriolytic substances, resulting in the leakage of protoplasm and the rupture of mycelium; Or produce antibacterial substances to inhibit spore germination by dissolving the cell wall or cell membrane of pathogen spores, resulting in cell wall perforation and deformity.
Bactericidal effect: Bacillus subtilis can produce bactericidal substances such as lipopeptides and proteins during the colonization and reproduction of crop root surface, root, stem and leaf, so as to kill crop pathogens and achieve disease prevention effect.
3. Enhance immunity and promote growth
Bacillus subtilis can secrete active substances, activate plant defense system, enhance crop immunity and disease resistance, and reduce or eliminate the harm of pathogens to plants. It can also promote the growth and development of seeds, seedlings and roots of a variety of plants, enhance the disease resistance of plants, and indirectly reduce the occurrence of diseases. Such as increasing the formation of auxin such as indoleacetic acid, stimulating crop root development and enhancing photosynthesis. At the same time, the substances that are difficult to absorb in the soil are transformed into substances that are easy to be absorbed by crops, so as to promote the absorption and utilization of nutrients by crops and improve the utilization rate of fertilizer.
Growth promoting effect: Bacillus subtilis has the function of dissolving phosphorus, which can convert invalid phosphorus in soil into effective phosphorus that can be absorbed by crops, promote the growth of crop roots and plants, and improve the disease resistance of crops.
4. Induce plant resistance
Bacillus subtilis can not only directly inhibit plant pathogens, but also enhance plant disease resistance by inducing plant disease resistance potential. For example, Bacillus subtilis, a Biocontrol Bacterium against rice sheath blight, can induce the activity of disease resistance related enzymes (POD, PPO and SOD) in rice leaf sheath cells to increase, so as to achieve the effect of disease resistance.
5. Improve soil structure
Bacillus subtilis forms a probiotic environment in soil, promotes the formation of aggregate structure, improves the ability of soil to retain fertilizer and water, increases soil porosity and promotes root growth. Specifically, accelerate the mineralization of nutrients and change nutrients from ineffective state and slow effect state to effective state and quick effect state. At the same time, accelerate the humification of nutrients, secrete phytase and degrade most of the phytate in the soil; Produce auxin, stimulate crop growth and improve seed survival rate and seedling emergence rate.
6.Increase soil urease activity
The soil treated with Bacillus subtilis showed stimulating effect on soil urease. The real bacillus subtilis is a biological agent, which has a good growth regulation effect on crops and soil.
