Preparation And Screening Of Seed Coating Agents For Controlling Root Rot Diseases In Cotton Seedlings

In this study,fungicides with good activity against the pathogens of the primary root-rot diseases and the red rot of Xinjiang roots were screened through indoor antibacterial experiments,and the suspensions,thickeners,and films were selected.Research on the processing technology of additives and seed coating agents etc.prepared 11 kinds of seed coating agents,and used their coated cotton seeds for functional verification research on safety,disease prevention,and determined the formulation of the seed coating agent that meets the target in order to prevent and treat cotton.Root-rot diseases in seedling stage provide theoretical basis and technical support.The main findings are as follows:1.Select 4 bactericides that meet the target.The activity of 11 fungicides against Rhizoctonia solani and Fusarium moniliforme was determined by the method of the growth rate of isolated plates in vitro,and4 kinds of fungicides with good effect on controlling root rot were screened,which were carbendazim,azoxystrobin,Difenoconazole,thiophanate-methyl.The EC₅₀ of Rhizoctonia solani isolates was 0.23 mg/L,0.20 mg/L,0.70 mg/L,and 0.73 mg/L,respectively.The EC₅₀ of Fusarium moniliformis was 0.23 mg/L,0.21 mg/L,and 0.44 mg/L,1.68mg/L,respectively.2.Select 3 seed coating additives.L₉（3³）orthogonal test design method was used to determine 11kinds of seed coating formulation suspensions,and the quality control indicators of various coating formulations were jointly determined to determine thickeners as 3%compound thickeners and film formers.1% sodium carboxymethyl cellulose.3.Study the seed coating preparation process.Through the study of feeding sequence,grinding time and physical property testing,it was determined that the sanding time of the seed coating agent was 45 min,the sanding speed was 1800 rpm/min,and the shear emulsification time of the high-speed shear emulsifier was 35 min.The indicators of the products all meet the industry technical standards.4.Seed coating agent coated cotton seeds are conducive to promoting seed germination and seedling growth.After indoor sand seed coating agent coated cotton seeds,germination potential,emergence rate,plant height,fresh weight per plant increased by 0%～39.83%,-4.17%～47.92%,1.06%～15.48%,7.87%～30.42%,there was no significant difference between dry weight of each treatm ent and CK;Field experiments showed that 11 kinds of seed coating formulations can also increase the growth of seedlings,and increase the cotton yield in different degrees.Seedling rate,root length,stem diameter,fresh weight per plant,and theoretical yield increased by-0.94%～8.27%,-0.62%～21.53%,-0.50%～8.99%,0.91%～102.33,and 2.26%～19.64%,respectively.5.Seed coating agents have a certain effect on the root rot of cotton seedlings.The indoor bacteria-inhibition experiment showed that the effect of various formulations on the control of Kuhn was between 10.89%and 62.18%,and that against red rot was between 35.33%and 75.59%.Field investigation results showed that:The effects of controlling the seedling blight and red rot of cotton were37.74%～67.30%and 25.25%～73.24%,respectively.Through comprehensive analysis,three seed coating formulations that meet the research objectives were selected,and through the field test,three target formulations were selected.They were M2（17.2%imidacloprid﹒carboxin﹒thiram）and M5（16.%thiamethoxam﹒difenoconazole﹒fludioxonil）,M8（13%thifluzamide﹒thiram）,the seedling rate of three seed coating formulations,root length,stem diameter,fresh single Heavy and theoretical yields increased by 0.22%～20.03%,7.66%～16.33%,5.24%～8.1%,27.13%～61.18%,2.85～22.77%,respectively,compared with CK,and the effect of controlling seedling damping-off in cotton was 37.74%～67.30%,the effect of preventing red rot is between 25.25%and73.24%.