Chitosan oligosaccharides (commonly known in agriculture as amino oligosaccharins, COS) are highly active substances derived from chitin through deacetylation and enzymatic hydrolysis. With excellent water solubility, high bioactivity, and multifunctionality, they have been widely applied in tobacco cultivation. Below are the key roles of COS in this field:
1. Pest and Disease Control
Controlling Root-Knot Nematodes
When combined with arbuscular mycorrhizal fungi, chitosan oligosaccharides significantly reduce the resistance indices of root-knot nematodes, including nematode count, egg mass count, reproduction index, and root-knot index, by 44.5%, 87.8%, 89.3%, and 79.5%, respectively.
By enhancing soil enzyme activity and optimizing the microbial community structure in the rhizosphere, chitosan oligosaccharides effectively suppress nematodes, providing excellent control against root-knot nematode disease in tobacco.
Preventing Tobacco Diseases
COS exhibit strong preventive effects against tobacco mosaic virus (TMV) and black shank disease. Their antibacterial properties also enhance the plant’s resistance to various diseases.
2. Promoting Tobacco Growth
Chitosan oligosaccharides boost root vitality, improve nutrient absorption efficiency, and promote overall growth and development of tobacco plants. When used in combination with arbuscular mycorrhizal fungi, they further enhance growth performance and improve the quality of tobacco leaves.
3. Alleviating Low-Temperature Stress
- Under cold stress, chitosan oligosaccharides protect tobacco seedlings by:
- Reducing oxidative damage;
- Increasing the content of osmotic regulatory substances;
- Enhancing antioxidant activity.
- A solution of 100 mg/L chitosan oligosaccharides has been shown to effectively mitigate the effects of cold spells, such as late spring frost, significantly increasing the survival rate of tobacco seedlings.
4. Enhanced Effect with Salicylic Acid
The combination of COS and salicylic acid spray yields superior effects compared to individual applications, including:
- Rapid and sustained enhancement of enzyme activity;
- Increased gene expression, boosting systemic acquired resistance;
- Lower malondialdehyde content and higher proline levels, thereby improving tobacco plant resistance to stress.
Treatment groups using this combination exhibited the lowest disease incidence rates and optimized the chemical composition of cured tobacco leaves, such as higher potassium content and reduced chlorine content. These results indicate that chitosan oligosaccharides, either alone or in combination, positively influence the quality of tobacco leaves.
5. Recommended Application Concentrations
- Salicylic acid solution: 1 mmol/L;
- Chitosan oligosaccharides solution: 120 mg/L.
Chitosan oligosaccharides serve as an efficient biostimulant in tobacco cultivation, offering remarkable benefits in pest and disease control, cold stress alleviation, and quality improvement. Their effects are particularly pronounced when combined with salicylic acid or arbuscular mycorrhizal fungi. Proper application of COS not only enhances the growth and development of tobacco plants but also improves the economic value of tobacco leaves, showcasing vast potential for broader agricultural applications.
