The Activity Study On Prescription Of Many Plant Saponins For Resisting Magnaporthe Oryzae In Vivo And In Vitro

Botanical fungicide is a kind of low toxicity,low residue biological pesticides, with the advantages of low pressure to environment,not easy to make the target bacteria become resistant, and so on. Rice blast is widely distributed,seriously harmful, and has been the first rice disease in southern China.The long-time utilization of chemical pesticide has caused many environmental problems, therefore, the reach and development of botanical fungicide to control rice blast fungus has vital significance. On the basis of previous research, the paper selected many plant formula and studied their activity in vitro and in vivo to develop formula for rice blast control.The main research contents and results were as follows:1、Inhibitory effects of Schima superba Gardn et Champ leaf, Sapindus mukurossi Gaertn pericarp, Magnolia Grandiflora Linn leaf, and Camellia oleiferaAbel leaf for rice blast were determined by peti dish method, the results showed that the four kinds of plant-active saponins etc. on rice blast have a strong inhibitory effect, the concentration for50%of maximal effect EC50of Schima superba Gardn et Champ and Sapindus mukurossi Gaertn were220mg/L and475mg/L respectively, Magnolia Grandiflora Linn and Camellia oleiferaAbel were950mg/L and1610mg/L respectively, the virulence of Schima superba Gardn et Champ and Sapindus mukurossi Gaertn to rice blast fungus was superior to that of Magnolia Grandiflora Linn and Camellia oleiferaAbel.2、With a quarter of the maximum effect concentration EC25values of the four kinds of plant-active saponin etc. as the middle level, combined with DPS data processing system,establish regression model Y=F (Xi, X2, X3, X4), obtained the relationship between test index-bacteriostatic rate (Y) and factors (the working concentration of Sapindus mukurossi Gaertn, Schima superba Gardn et Champ, Magnolia Grandiflora Linn and Camellia oleiferaAbel XA, XB, XCand XD), determining the plant saponin etc. content in the corresponding formula when getting the highest test index, forming11formulas.The good formulas were formula A, C, F, G, H, I, J and K, the EC50(mg/L) were193.1mg/L,132.5mg/L,487.0mg/L,452.8mg/L,256.1mg/L,492.3mg/L,470.7mg/L and257.0mg/L respectively.3、Make variance analysis to pot experiment results,results indicate that the formula K,C,H on rice rice blast of prevention and treatment effect all have the very good correlation, the EC50of prevention effect on rice varieties C101PKT were4939mg/L,7267mg/L, and7560mg/L respectively, the EC50of prevention effect on two optimal287rice varieties were5163mg/L,7705mg/L, and8305mg/L respectively;for the treatment, the EC50of C101PKT were5944mg/L,7986mg/L, and7986mg/L respectively, the EC50of two optimal287rice varieties respectively is6257mg/L,9516mg/L,9516mg/L and9247mg/L 4、According to the regulation of "pesticide registration data requirements" and the chemical pesticide environmental safety evaluation test guidelines method to determine the acute toxicity of plant saponin etc. and formula for bees and fish, the test results show that Sapindus mukurossi Gaertn, Schima superba saponin etc., formula K, C, H on bees and carp toxicity in48h LC50respectively were88.7mg/L and6.0mg/L,100.2mg/L and5.4mg/L,174.6mg/L and4.8mg/L,136.3mg/L and5.6mg/L,155.4mg/L and5.5mg/L,in accordance with the corresponding standard, single dose Sapindus mukurossi Gaertn, Schima superba. and formula K, C, H on bees and carp are median toxic.