| Wheat is one of the important food crops,its yield and quality is essential not only for the farmer's economic interests,but also closely linked with people's safety.Pests and diseases are important factors affecting wheat production,and at present the major control methods of wheat pest and diseases in China are still chemical control through which the indiscriminate use of pesticides has become the major source of agricultural pollution.Imidacloprid can effectively control seedling pests of rice,wheat,sugar beet,vegetables and other crops,especially have special effects for sucking insects,and tebuconazole can effectively control a variety of rust diseases,powdery mildew,wheat head blight of cereal crops.Seed coating treatment by imidacloprid and tebuconazole suspension seed coat agent are common measures to prevent and control wheat diseases and pests in agriculture.11 winter wheat cultivars common planted in Henan were selected in this study to research the seedling emergency rate,germination potential and germination index of seeds with or without coating by imidacloprid and tebuconazole,and according to the result we selected Aikang 58 varieties as experimental materials for further study.Influences of imidacloprid and tebuconazole with different used concentrations on seedling emergency,growth and resistance of the wheat were studied in field.also the influence mechanism of imidacloprid on seed germination and growth were studied by germination and pot experiments in aboratory test.The main results are as follows:1.In aboratory test about the influences of seed coating agent on seed germination and growth,we found that seed coating treatment delayed seed emergence,but the total seed germination rate of wheat were rarely affected.Seed coating agent effected the growth of wheat seedlings,and the impact were related to the concentration of seed coating agent.2.Field results showed that low concentrations of seed coating increased the rate of emergence of wheat,but high doses inhibited the emergence of wheat.After treated by seed coating agent,the growth indexs of wheat seedlings were not affected,but high concentration of seed coating agent significantly inhibited seedlings growth.Therefore,in production applications,selection of suitable seed coating agent and rational usage are essential to ensure the crop yield and quality.Pest survey results show that the amount of wheat aphids and sheath blight incidence of control group was significantly higher than treatment group,which imply the seed coating not only effectively control target pests and diseases,but also can improve resistance of wheat plants.3.Using sand culture method and pot culture method,wheat seeds water absorption,activity of germination and germination enzymes(?-amylase and protease)and root activity were studied with the seeds treated by two doses of imidacloprid FSC,one kilogram seed treated tiwh 6.67 g and 13.34 g preparation.We found that seed coating agent inhibited water absorption of seeds,and the inhibitory effect increased with the dose.Imidacloprid impacts on the activities of ?-amylase and protease,and high-dose treatment resulted in decreased enzyme activities.The root activity of wheat seedlings increased after seed coating treatment,and increased with the dose.4.The molecular mechanism of the influence of imidacloprid FSC on seed germination and growth of wheat.were further explored.RNA was extracted by Trizol,nitrogen cycle process relative expression of gene encoding enzymes were tested by real-time fluorescence quantitative PCR,and NR,Ni R,GS,GOGAT and GDH enzyme activity were measured,soluble protein and free amino acids contents were detected by the use of Coomassie brilliant blue staining method and ninhydrin colorimetric method.The results showed that imidacloprid could promote plant absorption and utilization of nitrogen by increasing enzyme activity related to nitrogen metabolism,and provide guarantee for plant basic life activities. |
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