Research On Complex Biological Seed Coating Against Soybean Root Rot

Biological seed coating agent is the most common method to treat the soybean which can prevent and control soybean root rot disease, it can acquire almost the same control effect of chemical seed coating. In addition, biological seed coating agent can improve soil statement and promote the growth of plant. However, some shortcomings exist in the previous two types biological seed coating agent: one type of agent which use single biological control strain as active material, will appear lag phenomenon which lead the effect of biocontrol in field is low, due to the field soil nutrients is different from the culture medium. The other type of agent which use biocontrol bacteria fermentation or metabolites as active material, does not have the persistent effect of controlling the plant pathogens. At the same time, some excellent biocontrol strains such as Chaetomium have not been studied as the biological seed coating agent. Therefore, to combine the above two kinds of biological seed coating agents, it is more valuable to develop composite biological seed coating agent which consist both biological control strains and biocontrol bacteria metabolites and take advantage of their seed function to compensate for the disadvantages of seed coating.In this research, complex biological seed coating consist of 1.5% chitosan as filmogen and three kinds of active materials including Chaetomium ascocarp,metabolitesh and Trichoderma viride chlamydospore. First, three kinds of active materials was prepared by using specific medium, then we find that the three active substances can coexist in the biological seed coating and can play their respective role in biocontrol by measuring the biocompatibility of three active substances. Through the experiment on film-forming and water-soluble, 1.5%chitosan was screened as film-forming agent.In this study, biological seed coating processing was determined, the effect of biological control was tested. Through flatbed confrontation experiment, it is obtained that Trichoderma chlamydospore powder and Chaetomium ascospores powder in a mass ratio of 1: 1, on the fourth day begin to against Rhizoctonia solani and Fusarium oxysporum, and the inhibition rate to the two pathogens are 88.8%and 86.6% 1 mg / m L Chaetomium metabolites can restrain the two plant pathogens at second day, and in the ninth day of respectively inhibition rate up to 66.6% and53.3%. This shows that the preventive effect of Chaetomium metabolites is earlier than two biocontrol strains and Chaetomium metabolites can be used as a first line of defense the early invasion of pathogens. Therefore, the complex biological seed coating of this study, in theory, can solve the existing problems on biological seed coatings.