Studies On A Bio-Seed Coating Agent Of Trichoderma And The Mechanism Of Disease Control

A new Bio-Seed Coating Agent of Trichoderma against the main soil-borne diseases of maize,of which the active ingredients is Trichoderma,chitosan and phenazine-l-carboxylic,and the effect of disease control and growth of the agent was tested in pots and fields,and both the physiological and ecological mechanisms of disease control were studied in this paper.The feasibility of the complex of Trichoderma,chitosan and phenazine-1-carboxyl ic was studied,it is found that not higher than 2 000 mg/L of chitosan and not higher than 1.0 mg/L of 1% phenazine-1-carboxylic have no inhibition on Trichoderma growth and spore germination,and the seed germination test also improves that the concentration can progress seed germination and seed vigor. Inhibitions of chitosan or phenazine-l-carboxylic,as well as the mixtures of them,on Rhizoctonia growth was tested by the the method of growth rate.Effects of the combinations of two bio-pesticides on biocontrol efficiency of Trichoderma were also compared.In general,it was found that either the single or the combinations of the bio-pesticides has strong inhibition on Rhizoctonia growth,the combinations could also increase the biocontrol efficiency of Trichoderma, and the best ratio which has the lowest EC50 againse Rhizoctonia was 6 to 4 of chitosan to phenazine-1-carboxylic.The field control effect of the agent was tested in three sites.It is found that it has a control effect against rough dwarf but has no effect against stem rot and sheath blight of which the incidence were both too low in shanghai site,it decreased the disease index of small leaf blight and sheath blight and the incidence of stalk rot in Guangdong,it reduced the rate of ear hanging,lodging and the number of pests,release the severity of stalk rot and maize borer.It also can increase the the rate of emergence of maize seedlings and the heights of adult and mature plant stage.the output indicators and the yield of maize were the highest after treatment as 1:20 of agent to seed,the yield was increased by 4.92% per mu.Activity Changes of superoxide dismutase (SOD),peroxidase dismutase (POD),polyphenol oxidase(PPO)and malonaldehyde content of the leaves ant roots of maize which was inoculated with Fusarium was tested,it is found that the agent can significantly increase the activities of POD and PPO and decrease the accumulation of malonaldehyde of the roots of maize,which shows that the agent has some role in the induction of defense enzymes of maize roots.But it did not increase the activities of related enzymes and decrease the accumulation of malonaldehyde of the leaves of maize,this may be that the agent has not induce the systemic resistance of host. The quantity of the three categories of soil microorganisms was determined and it was found that the agent could significantly increase the total number of microorganisms or bacterias in the soil,and decrease the total number of fungis or actinomycetes,and the pesticides of agent plays a major role in the impact of the quantity of soil fungis and bacterias.