The Preparation Of Pesticide-loaded Hydrogel Modified By Silica Microcapsule And Its "Partner" Effect On Field Rape Production

Rape is an important oil crop in China,which is threatened by a variety of diseases and pests.At present,China mostly adopts the strategy of comprehensive control.In this paper,a kind of silica modified polymer drug loaded water gel was designed and prepared for field rape production,which provided a basis for rape growth and comprehensive control of diseases and pests.We use sodium carboxymethyl cellulose（CMC）and starch as raw materials,use their high molecular chains to wind each other to form a skeleton,in-situ coat pesticide technical drugs,add nano silica drug loaded microcapsules（SMC）,add them to Fe Cl₃ solution after stabilization,crosslink and solidify them to form a hydrogel gel granule preparation,and then apply the preparation to field trials.The details are as follows:1.Preparation and release properties of silica microcapsule modified drug loaded water gel.Silica drug loaded microcapsules（SMC）were prepared by in-situ coating drugs（Uniconazole（UNI）,carbendazim（MBC）,imidacloprid（IMI）,indoleacetic acid（IAA）,etc.）with microemulsion method.The ethyl acetate solution of the drug and the aqueous solution of the surfactant were mixed to form a micro lotion.After the added tetraethyl orthosilicate（TEOS）is hydrolyzed in the aqueous phase,it is orderly arranged under the action of oil-water interfacial surfactant and further condensed to form SMC.In addition,CMC solution and starch solution are mixed,a certain amount of SMC and drugs are added,the mixture is added to Fe Cl₃ solution drop by drop,stirred and solidified at room temperature,and the obtained particles are the modified drug loaded water gel preparation after drying,with a drug loading of 100-120 mg/g.2.Application of drug loaded hydrogel in rape field production.Four kinds of hydrogels loaded with Uni,MBC,IMI and IAA were used in the field experiment of rape to investigate the safety of the drug system on the emergence of rape seeds,and the effects on the growth,development and health of rape seedlings.The hydrogel preparation was seeded simultaneously with rape seeds of Huayouza62 and Huayouza62R at three application gradients of 18,27 and 36 mg/m².Except that IMI hydrogel has about 50%inhibition effect on the emergence of rape seedlings,other hydrogel preparations have no obvious inhibition effect,indicating that the preparations generally have good safety on seeds.The root length,seedling height,fresh weight,dry weight and leaf SPAD value were tested at 38 days（early seedling stage）and 70 days（late seedling stage）of rape growth.Uni hydrogel had a delaying effect on the growth of above ground part of rape at 38 days,and the seedling height was shortened by 32.5-35.0%;After 70 days,the delay effect was no longer obvious,and the SPAD value increased by 12.5%,indicating that the health status of rape was improved.At 38 days,MBC hydrogel increased root length and seedling height by 2.86-31.4%and 9.62-45.5%respectively,showing a promoting effect on rape growth;At 70 days,the growth of Huayouza62 showed a promoting effect,and the growth of Huayouza62R showed a inhibiting effect.IMI hydrogel showed a trend of low concentration promoting and high concentration inhibiting the growth and development of rape at 38 days;To 70 days,the growth of Huayouza62R showed inhibition effect,and the SPAD value of leaves showed a trend of low concentration inhibition and high concentration promotion.IAA hydrogel preparation did not show significant effect at 38days.On the 70th day,the root growth of Huayouza62 was promoted,and Huayouza62R was inhibited.The SPAD value of rape leaves increased by 12.0%,indicating that the health status of rape was improved.The results of Leaf SPAD value test on the 135th day showed that only UNI and IAA hydrogels still showed the effect of improving the SPAD value of rape,and the health status of rape was improved.In the mature stage,the straw breaking strength was tested.The above results showed that the modified hydrogel preparation had good seed safety,basically had no obvious inhibitory effect on seedling growth,and could promote the improvement of plant health to a certain extent.The effective effect of the preparation lasted for 135 days,covering the key seedling stage from sowing to rape growth,and played a good"companion"role in rape growth.Part of the hydrogel preparation can significantly improve the lodging resistance of rape at a certain concentration.These experiments provide valuable reference for improving the quality of rape production.