| Seed treatment agents play a very important role in crop production,seed standardization.Phytotoxicity of seed treatment agents to crops are caused by the quality of seed treatment agents,improper dosages and improper formulations,environments and climates.The phytotoxicity of seed treatment agents to crops shows as abnormal seed germination,seedling growth deformity,growing slowly and deduction of crop production.Proper application of seed treatment agents and proper preventive measures and the application of antidotes can reduce the injury of seed treatment agents and the loss of farmers.Our experiments studied the characters of the phytotoxicity caused by the seed treatment agents which were widely used in production and the concentrations caused by the occurrence of the phytotoxicity of the seed treatment agents.We studied and screened potential antidotes which could prevent and reduce the occurrence of the injury of seed treatment agents to crop growth.The mitigation effects and mechanisms of the antidotes also had been studied by measuring morphological,physiological and biochemical indexes of the test crops.The results of our research as follows:1.The dosages causing phytotoxicities of the crops by seed treatment agents and the symptoms of the phytotoxicities.Our research results of the effects of different seed treatment agents to wheat,maize,peanut showed that height was suppressed most obviously after the wheat and maize dressed by seed coating agent containing tebuconazole at the dosage of 0.32 g a.i./kg and 1.2 g a.i./kg respectively.When the seed of wheat was coated by triadimefon at the dosage of 1 g a.i./kg,the symptoms of phytotoxicity were observed obviously and the most inhibition to the plant was the height of the plant.The plant height was inhibited apparently after the seeds of the wheat were treated with epoxiconazole at the dosage of 0.35 g a.i./kg and the later growth of the wheat could not restore to normal.The symptoms of phytotoxicity were obvious and root length,plant height,fresh and dry weight were significantly affected when the peanut seeds were dressed with chlorpyrifos at the dosage of 96 g a.i./kg.When the peanut dressed by seed coating agent of imidacloprid at the dosage of 8 g a.i./kg,the symptoms of phytotoxicity were obvious and the height and dry weight of the plant decreased significantly under low temperature conditions.2.The mitigation effects of some antidotes to the phytotoxicities of seed treatmentagents containing tebuconazole,triadimefon,etc.Seed soaking of ferrous sulfate,manganese sulfate,borax,zinc sulfate and ammonium molybdate could relieve the phytotoxicities of wheat and maize effectively caused by seed treatment agent containing tebuconazole.Comparing to the control treatment,the height of wheat which were treated with borax and zinc sulfate increased 3.84 cm and 3.8 cm(increasing 35.5% and 35%)respectively.Meanwhile,the chlorophyll content increased apparently and the contant of MDA,proline and the activity of SOD in the plant decreased in the treatments of borax and zinc sulfate.The antidotes of Hauw-A,gelatin,xanthan gum,Hauw-S,Hauw-JP alleviated the phytotoxicity of seed coating agent of tebuconazole significantly.The composite components of Hauw-HMA also mitigated the phytotoxicity of tebuconazole obviously,and the plant height of wheat treated with the composite component increased 3.83cm(or 38%)compared to the treatment of tebuconazole.Gelatin,Hauw-A,Hauw-S,Hauw-JP and Hauw-JN showed significant mitigation effects on the phytotoxicities of triadimefon to wheat in morphological,physiological and biochemical indexes.The root length and plant height of wheat treated with arabic gum increased 6.8 cm and 4cm(increasing 84.7% and 45.3%)compared to the treatment of triadimefon and the chlorophyll content increased and the proline content and the activity of SOD of the plant decreased obviously when the seeds of wheat were treated with Hauw-A.3.The effects of different antidotes to the phytotoxicities of seed coating agent of imidacloprid to peanut under low temperature conditions.The symptoms of the phytotoxicity were obvious after seeds of peanut were dressed by seed coating agent of imidacloprid under low temperature conditions.The root length of peanut treated with antidote ammonium molybdate could increase 10.2 cm compared to the treatment of imidacloprid.The treatment of ammonium molybdate could increase chlorophyll content and root activity of peanut plant and decrease the content of MDA,the activity of SOD and the content of soluble sugar.Seed soaking of manganese sulfate,borax,zinc sulfate,ammonium molybdate could effectively alleviate the phytotoxicities of seed coating agent of imidacloprid under low temperature conditions.This paper studied the dosages and concentrations of the seed treatment agents containing tebuconazole,triadimefon,chlorpyrifos and imidacloprid causing the phytotoxicities to wheat,maize and peanut.The symptoms of the phytotoxicity were observed.The mitigating effects of some antidotes to the phytotoxicities of the seedtreatment agents to the plants were examined.The changes of the physiological and biochemical indexes in the plants were determined when the phytotoxicities and the mitigating effects occured on the plants.The research indicated that some antidotes we tested demonstrated significant mitigating effects to the phytotoxicities of the seed treatment agents containing tebuconazole,triadimefon and imidacloprid in low temperature conditions to the tested plants in laboratory.The application of the effective results of these studies in crop productions and the further studies of the antidotes of the phytotoxicity of the seed treatment agents will have obvious significance to prevent and reduce the phytotoxicity of the seed treatment agents. |
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