The Preparation Of Microcapsuled Tebuconazole Seed Coatings Formulation And Its Safety Mechanism On Maize

Tebuconazole is a triazole and systemic fungicide,which has excellent biological activity, low usage, wide scope of application, and as a seed treatment,it is effective against wheat powdery mildew and maize head.But excessive amounts of tebuconazole can damage seeds and reduce germination.Microencapsulation technology can microencapsulate the active ingredients, and then microcapsule control it's release, playing a role of sustained release. Microencapsulated tebuconazole, as a seed treatment, can effectively reduce the direct contact between pesticide with the seed, so as to reduce or eliminate phytotoxic effect on crop.In this study,cellulose acetate butyrate(CAB),ethyl cellulose(EC),polymethyl methacrylate (PMMA), were used as thepolymer matrix,and tebuconazole was used as active ingredient. Microcapsules were prepared by the oil-in-water emulsion and dissolvant evaporation process with low cost,which was easy and simple to handle,and the particle size of the microcapsules was tiny.A laser particle size analyzer and scanning electron microscopy were using to measured particle size of microcapsules, the particle sizes of microcapsules with different shell materials were diverse. in the range between 0.5～14μm, microcapsules of EC obtained the maximum size, and microcapsules of CAB (35-39) made the smallest particle size.The encapsulation efficiency and the release rate of microencapsulated tebuconazole was testd by mixing the formulation with water.the amount of the tebuconazole in the solution was determined by HPLC-MSD. The encapsulation efficiencies of microencapsulated tebuconazole with different materials were all above 90%, which show a high level of microencapsulation,and the differences of the different materials were not notable. The encapsulation efficiency of the microcapsules based on PMMA was the highest and The encapsulation efficiency of the microcapsules based on ethyl cellulose wad the lowest (90.63%).The release of tebuconazole from the matrix material into the water environment corresponds to Fickian diffusion, diffusion rates of tebuconazole from different matrix materials were different, which from ethyl cellulose microcapsule released fastest, PMMA slowest, there was no burst release, which reached the controlled release purposes. Tebuconazole effects on the metabolism of isoprene in plants, inhibiting gibberellin biosynthesis, inhibiting the catabolism of abscisic acid(ABA), which changes the balance of the plant hormones. the regulating hormone levels can control of plant growth and development effectively. Tebuconazole microcapsules formulation based on different matrix materials (such as CAB, ethyl cellulose and PMMA) were used as seed coating treatment on maize. the determinations containing the rate of emergence, the height of the seedling and the weight of stem,leaf and root, indicated that high concentration of tebuconazole inhibited emergence and primary growth of maize seedling seriously. Microcapsules seed coating formulation relieved the inhibition of tebuconazole effectively.The determinations about the amount of chlorophyll and activity of phenylalanine ammonialyase (PLA) of maize seedlings evaluated effect of tebuconazole on seedling growth and disease resistance.The determinations of the GA and ABA content indicated that high concentration of tebuconazole effected the GA content of stem and ABA content of root heavily,while microcapsules seed coating formulation relieved the influence of tebuconazole effectively.