Studies On The Manufacturing And Application Of Chitosan Oligosaccharide As A New Biopesticide

As a new efficient biopesticide, chitosan oligosaccharide, has a broad spectrum of bacteriostatic activity while being non-toxic to human-beings and livestock, and also induces plant’s disease resistance. Then an effective way to decrease the use of chemical pesticide can be developed. Using enzyme hydrolysis method for chitosan and ultrafiltration membrane separation technology, our laboratory prepared chitosan oligosaccharides(COS) in different molecular weights. The antifungi influencing factors on plant pathogenic fungi in vitro were studied with the method of growing rate and M38-A2. on that basis, the potting experiment was carried out. Specific research results are as follows:1. COS samples in molecular weight of3000,10000, and50000was prepared with Chitosanase hydrolysis method and ultrafiltration membrane separation technology, and analysed by TLC and HPLC.2.Common plant pathogenic fungi including xanthomonasoryzae, piricularia oryzae, rhizoctonia solani, verticillium daltliae, F.oxysporum, phomopsis asparagisacc, and fusarium oxysporum f.sp conglutinans were decided as the experimental subjects, and the COS’s antifungi effect on plant pathogenic fungi was studied. It’s resulted that COS had an inhibiting effect on most plant pathogenic fungi, such as verticillium daltliae, rhizoctonia solani, phomopsis asparagisacc, xanthomonasoryzae,and fusarium oxysporum f.sp conglutinans.3.The effect of different of COS’s molecular weight and consistency on plant pathogenic fungi was studied with verticillium daltliae, rhizoctonia solani, phomopsis asparagisacc, xanthomonasoryzae, and fusarium oxysporum f.sp conglutinans as the experimental subject.It’s indicated that COS’s molecular weight was an very important influencing factor on some plant pathogenic fungi,(eg.fusarium oxysporum f.sp conglutinans, verticillium daltliae and rhizoctonia solani:Mw3000>Mw10000>Mw50000. However, the result was got on the contrary for phomopsis asparagisacc.) The EC50was investigated with COS(Mw3000) added into the medium.The results show that:the value of EC50was0.1580mg/mL to verticillium daltliae,0.1970mg/mL to phomopsis asparagisacc,0.1590mg/mL torhizoctonia solani, and0.1680mg/mL to fusarium oxysporum f.sp conglutinans. The growth of fungal hypha was seriously inhibited with COS’s effective EC50.4. Furthermore, COS’s antifungi effect on plant pathogenic fungi was illustrated using the internationally accepted method of M38-A2. It’s revealed that:the MIC to verticillium daltliae was41.686μg/mL、43.797μg/mL、45.563μg/mL when COS(Mw3000,Mw10000,Mw50000)was used respectively,the MIC to fusarium oxysporumf.sp conglutinans was83.313μg/mL、87.594μg/mL、91.125μg/mL.5. Studies on COS’s control efficiency for rice and cabbage were carried out.The results of pot culture experiments presented:0.1g/L COS could prevented the main common diseases of the two plant. The relative biocontrol efficacy for fusarium oxysporum f.sp conglutinans and Xanthomonas oryzae were36.36%and36.19%. In addition, it’s also indicated that COS could decrease plants’morbidity.6. POD and CAT’s enzyme activity, MDA and soluble protein contents variations were compared of different treatment,and thus, preliminary exploration for chitosan oligosaccharide’s resistance mechanism was infered. It is deduced that COS can be use as an exciton to induces plants’disease resistance.In conclusion, as a new efficient biopesticide, chitosan oligosaccharide enjoys such effects as enhancing plants’disease resistance, promoting their seeding germination, and boosting their growth. What is more, COS has various advantages involving pollution-free, long duration, and super efficiency. All these indicated that COS has a promising perspective and great potential in industrial.