As a safe biostimulant, chitosan oligosaccharide is widely used in agriculture and can significantly improve the quality of agricultural products. Chitosan oligosaccharide has gained a large number of loyal fans due to its strong agricultural functionality and broad-spectrum antibacterial properties, especially its excellent effects on plant immunity and stress resistance, and inhibition of nematodes, good choice for fertilizer formulation.
Ten functions of chitosan oligosaccharide
(1) Improve crop disease resistance
Treating plants with chitin and its derivatives before the plants are infected can produce a sensitizing effect, and the treated plants can show a higher preventive effect than normal plants when they are infected by diseases and insect pests again. It can be toxic to certain fungi, bacteria, viruses and pests, and induce plants to activate their defense systems.
Chitosan oligosaccharide cannot directly inactivate viruses, but it has a significant inhibitory effect on the replication and long-distance movement of viruses in plants. Effects of plant viral diseases. Use before the outbreak of the virus can prevent the occurrence of viral diseases, can induce the resistance of plants to virus proliferation and long-distance movement in the body, and its inducing activity does not depend on the R gene of the host, and when used after the outbreak of the virus, can inhibit the spread of the virus to new leaves. . It has a broad-spectrum effect on fungi, and has different degrees of preventive effect on almost all fungal diseases, including powdery mildew, downy mildew, black mole, and blight, etc. It is mixed with targeted fungicides, such as enoyl Morpholine, flusilazole, pyraclostrobin, thifuramide, ethiolycin, tebuconazole, cyanobacteryl, etc., can achieve both internal and external considerations, and achieve the effect of reducing drugs and increasing efficacy.
(2) Activating the plant's own innate immune system
As a major component of the cell wall of fungal pathogens, chitin stimulates an immune response in plants. There are a variety of pattern recognition receptors on the cell membrane of plants, which trigger innate immune responses by recognizing some common and conserved molecular motifs (ie, pathogen-related molecular patterns) on pathogens. An important part of. Chitosan oligosaccharide can bind to receptors on plant cells, stimulate the production of resistance signal molecules, and through signal transduction, stimulate the expression of resistance genes and produce resistance substances, so as to achieve the purpose of disease control.
Generally, the degree of polymerization of chitosan oligosaccharide is between 2 and 10, and the distribution of acetyl groups on the chitosan molecular chain is random, and its number and position have a great influence on the activity of chitosan oligosaccharide. The degree of deacetylation of chitosan oligosaccharide varies greatly in the deacetylation process, that is, under the same conditions, the higher the degree of deacetylation, the more free radical content, and the higher the antibacterial activity of chitosan oligosaccharide.
(3) Improve crop stress resistance
In the process of agricultural production, drastic changes in the external environment will cause huge irreversible damage to plants. In northern greenhouses and early spring open-field crops, low-temperature freezing damage often occurs. When the weather is abnormal, citrus and grapes in the south will also experience freezing damage or freezing damage, resulting in weak seedlings, wilting leaves, falling flowers and fruits, and fruit deformities. Low ground temperature also causes root system damage. The absorption capacity decreases, and the photosynthetic efficiency is low, which directly affects the crop yield and quality. For example, low temperature environment can easily lead to reduced fluidity and peroxidation of plant cell membranes, causing damage to plant cells. Chitosan oligosaccharide can increase the content of cold-resistant substances such as soluble protein and soluble sugar, reduce the level of membrane lipid peroxidation and increase membrane permeability. It can maintain the high photosynthetic intensity of crops and effectively resist the damage of low temperature to crops. Miura Baicao Zhang Jianbo's test shows that chitosan oligosaccharide has a significant effect on inducing cold resistance in plants, and the effect is significant when used 1 to 7 days in advance. In addition, through the spinach test under high temperature environment, Zhang Jianbo found that the degree of damage to the spinach leaves sprayed with 500 times Baijing (3% amino oligosaccharide) was much lower than that of the control, indicating that chitosan oligosaccharide has anti-heat, The effect of heat resistance is obvious, and the heat resistance of chitosan oligosaccharide is of great significance for the use of chitosan oligosaccharide in high temperature seasons.
In addition, by treating corn seeds and seedlings with Cu2+ and Mn2+ complexes of chitosan, the complexes can significantly increase the SOD activity in the leaves of corn seedlings and reduce the oxidative stress of superoxide anion free radicals caused by salt stress, especially in the Under the action of chitosan-copper complexes, the content of proline in maize seedlings decreased from 1684µg·g-1 in blank to 913, which indicated that the salt tolerance of maize seedlings could be significantly improved.
(4) Improve rhizosphere microbial population and inhibit nematodes
Many organisms in the soil (such as plants, bacteria, fungi, etc.) can produce chitinase, which breaks down the chitin tissue in fungi and insects and destroys its structure. Adding chitosan to the soil promotes the reproduction and activity of microorganisms, these microorganisms produce more chitinase, antibiotics and toxins, or directly compete with harmful organisms for nutrition, or directly parasitize, or activate plant defense systems, etc. In this way, the control level of pests with chitin composition structure is increased. Chitin oligosaccharide has the function of assisting line inhibition. Chitin oligosaccharide can induce plant roots to secrete chitin hydrolase and destroy chitin in the nematode egg cell wall; Foshan Yinghui experiment found that chitosan oligosaccharide can repair damaged roots and promote It takes 1-2 days to take effect after rooting, and after 5 to 7 days, it is obvious that new roots grow, which relieves the phytotoxicity of thiazophosphine and synergizes with thiazophosphine.
(5) Stimulate the rooting of crops
After the chitosan oligosaccharide is absorbed by the plant, it induces the plant to produce auxins such as indole acetic acid and gibberellin, which stimulates the root development of the plant. , can stimulate the early germination of crops, the capillary roots are many and long in the seedling stage of the crop, the potato has a strong absorbing root system in the middle and late stages, better use of fertilizer and water, and become the basis for crop drought resistance and yield increase. 0.05~0.2% concentration of cotton seed coating treatment for 30min can stimulate seed germination, improve germination rate and increase the number of cotton bolls per plant.
(6) Promote the early growth of plants
Chitosan oligosaccharide has the effect of antibacterial and inducing plant production of chitinase in plant cells and tissues, and can improve enzyme activity, promote protein synthesis, regulate the closing and opening of plant genes, and induce the synthesis of auxin indoleacetic acid (IAA). . Stimulate a variety of plant growth and development genes, synthesize bioactive substances that are beneficial to plant growth, activate plant cells, and promote the rapid growth and development of plants.
Because chitosan oligosaccharide treatment of plant seeds can promote uniform emergence, thick main stem, early ridge sealing, early growth of plants, shortened vegetative growth time, and can bloom 2 to 3 days earlier, laying a foundation for increasing production. The harvest period can also be 3 to 5 days earlier than the blank control. The test found that low concentration of chitosan oligosaccharide (optimal concentration 0.1mg·L-1) treated cucumber seeds and seedlings could promote the growth of cucumber seedlings. Compared with the control group, various growth indexes were significantly increased.
(7) Increase crop yield and improve the quality of agricultural products
Because chitosan oligosaccharide stimulates the root system, promotes early growth, and improves the photosynthetic efficiency of leaves, especially under the condition of insufficient light in the greenhouse, the yield of plants is significantly increased. In the case of hail disaster, Zhang Jianbo's experiment showed that the control yield of Atlantic varieties was 1951kg per mu in 15 days before harvest, and the yield of 100 ml per mu can increase by 334 kg, the yield increase rate is 17.1%, and the 150 ml per mu can increase the yield by 21.6%. It shows that Baijing spray ditch promotes the early root system of potato, the early growth of the plant, and the obvious increase in the later yield, and the larger the dosage, the more obvious the yield increase. At the same time, the uniformity is increased, which can improve the commodity rate of the first-grade potato chips.
After spraying chitosan oligosaccharide solution 3 times in the growing season, the quality of citrus has been greatly improved, which is mainly reflected in the increase of vitamin C content by 20%, the increase of soluble total sugar by 13%, the increase of soluble solid content by 6%, and the increase of solid-acid ratio. 52%, and citrus titratable acid content decreased by 21%. Similar results were obtained on grapes, watermelon, and tomatoes.
(8) Degradation of chemical pesticide residues in plants
Chitosan oligosaccharide can induce and improve the P450 enzyme activity in plant cells and degrade chemical pesticide residues in plants. The degradation effect of permethrin is remarkable, reaching 100%.
(9) Safety and efficiency
Mixing with fungicides can greatly reduce the amount of fungicides, up to 90% of the amount of chemical pesticides, and has obvious effects on preventing crop diseases and improving yield. In addition, chitosan and its derivatives can be encapsulated with Trichoderma, Beauveria bassiana, Bacillus thuringiensis and other biological bacteria to make preparations, which is not only conducive to the storage and transportation of these microbial preparations (as carbon and nitrogen sources for microorganisms), can also promote their use.
(10) Preservatives for fruits and vegetables
Post-picking losses of fruits and vegetables are mainly caused by fungal infections, physiological diseases and physical injuries. The preservation of fruits and vegetables is based on controlling the activities of microorganisms to slow down their normal life activities, and maintain the natural storage and disease resistance of fruits and vegetables, that is, inhibit the respiration of fruits and vegetables, prevent ethylene production or reduce ethylene concentration.