The Pathogenicity Of Pathogens On Maize Seeds And The Sensitivity Of Pathogens To Fungicides Under Low-temperature Stress

In recent years,injury of maize seed coating occurs frequently under low temperature,causing poor seedling emergence and serious economic loss.In this study,we took the effects of low temperatures on soil pathogens,fungicides and maize into consideration,and analyzed the pathogenicity of Fusarium spp.and Pythium spp.on maize,and the sensitivity of Fusarium spp.and Pythium spp.to different fungicides under low-temperature stress.We also analyzed the mechanism of tebuconazole's phytotoxic effects on maize under low-temperature stress.Conclusions are as follows:1.In the temperature range of 10 ?-25 ?,compared with 25 ?,F.graminearum was more pathogenic on maize seeds with low seed germination rate and shoot emergence rate,which caused low seedling emergence rate at 10 ? and 15 ?;But the effect of F.verticillioide on maize seeds showed no signigicantly difference between 25 ? and 10 ?-15 ?;F.graminearum and F.verticillioide had low risk of seedling rot at low temperature.Compared with 25 ?,the sensitivity of F.graminearum to difenoconazole,prochloraz and fluazinam,and the sensitivity of F.verticillioide to fluazinam decreased at 10 ? and 15 ?,which may increase the risk of injury.2.In the temperature range of 10?-25?,compared with 25 ?,P.inflatum and P.ultimum were more pathogenic on maize seeds with low seed germination rate and shoot emergence rate,which caused low seedling emergence rate at 10 ? and 15 ?;But P.aphanidermatum was less pathogenic on maize seeds at 10 ? and 15 ? than 25 ?;P.ultimum was more pathogenic to maize seedlings at 10 ? and 15 ? than at 25 ?,which increased seedling rot and caused low seedling emergence rate.Compared with 25 ?,the sensitivity of P.aphanidermatum and P.ultimum to pyraclostrobin,and the sensitivity of P.inflatum decreased at 10 ? and 15 ?,which may increase the risk of injury.3.In the temperature range of 10?-25?,the competitive ability of F.graminearum was higher than that of P.ultimum,and F.graminearum can overgrow on the colony of P.ultimum;The period of overgrowing on the colony of P.ultimum depended on inoculation intervals and incubation temperature;.Shorter inoculation intervals and lower temperature may increase of P.ultimum infection and increase the risk of getting injury at low temperature.4.In the temperature range of 10 ?-25?,the aggressiveness and pathogenicity of F.graminearum gradually decreased as temperature decreased,but the aggressiveness and pathogenicity of P.ultimum gradually increased as temperature decreased.After seed treatment with tebuconazole,the aggressiveness and pathogenicity of F.graminearum significantly decreased and the aggressiveness and pathogenicity of P.ultimum has no significant difference with control treatments.In the combined fungi treatmets,compared with normal temperature,low temperature worsen the pathogenicity on maize root and tebuconazole treatment can only decrease the pathogenicity of F.graminearum.The results indicated that maize seedlings had ta risk of injury at low temperature when maize seeds were coated only with tebuconazole.5.In the temperature range of 10?-25?,with the decrease of temperature,the rate of maize seed germination and seedling growth decreased,but tebuconazole content of maize root and embryo increased.The accumulation of tebuconazole in corn tissue may increase the risk of plant growth inhibitory effect.In conclusion,In this study,we analyzed the interaction of low temperature,soil pathogens,fungicides and maize.The results revealed the mechanism of maize injury caused by fungicide seed coating under low temperature stress,and proposed technical principles of pesticide application to solve maize injury under low-temperature stress.The results will provide a theoretical guidance for safe application of fungicide seed treatment under low temperature.