Comparison Of Resistance Of Sea-island Cotton Varieties (Lines) To Fusarium Wilt And Evaluation Of Biological Control Of Antagonistic Bacterial

Cotton Fusarium wilt,a fungal disease caused by Fusarium oxysporum,is the most common destructive disease in cotton growing season.In this study,20 kinds of island cotton varieties with different resistance to Fusarium wilt and 20 hybrid population of 06-146 and Xinhai 14 were selected for identification of resistance and analysis of yield traits by inoculation.The cotton diseased stem with Fusarium wilt was collected,the strong virulence pathogenicity fungus were isolated and screened.To determine the virulence of indoor hybrid bactericide by using hybrid cotton line female parent-resistant Verticillium wilt resistant variety Xinhai 14 as target material At the same time,collecting the root peri soil of disease resistant cotton material,and the antagonistic bacteria with better biocontrol effect were obtained,which provided the theoretical basis and scientific basis for the cotton disease resistance breeding and disease control.The following conclusions were derived:1.20 island cotton varieties and 20 hybrid populations of 06-146 and Xinhai 14 were selected for indoor and field resistance identification and analysis of yield characters.The island cotton resistant varieties accounted for 35%,including island cotton varieties 06-146,Xinhai 13,Xinhai 20,Xinhai 21,Xinhai 29,N9247 and C06015;The percent of resistant in hybrid populations of 06-146 and Xinhai 14 was65%including 10702,10719,10724,10727,10749,10765,10787,10862,10876,10880,10889,10892and 10902.According to the analysis of yield characters,there was a significant negative correlation between the relative disease index and boll number per plant among 20 island cotton varieties,the correlation coefficient was-0.672.The relative disease index of 20 hybrid population of 06-146 and Xinhai14 was significantly negatively correlated with the number of bolls per plant,the correlation coefficient was-0.599;And the correlation index was-0.267 and-0.265 of the number of seed per boll and the total weight of single boll,showed significant negatively correlation.2.By separating and purifying the strains of cotton Fusarium oxysporum,the bactericide 100 billion/g Bacillus subtilis WP,8%Ningnanmycin AS,0.3%Tetramycin AS and 80%Mancozeb WP of manganese zinc were selected to test the virulence of the strong virulence pathogenicity fungus numbered DD64,DD89,DD11 and DD22.The DD64 and DD89 strains isolated from northern Xinjiang were determined.The highest bacteriostatic rate of 100 billion/g bacillus subtilis WP was 96.47%and 95.29%,followed by0.3%Tetramycin AS.The strains DD11 and DD22 isolated from southern Xinjiang were determined to have the best antibacterial effect with 0.3%Tetramycin AS,97.91%and 99.35%,followed by 100 billion/g Bacillus subtilis WP.The virulence of 8%Ningnanmycin AS was the highest among DD64 and DD89.EC₅₀ values were 0.044 mg/L and 0.046 mg/L.In production,0.3%Tetramycin AS is recommended to be used in the early stage of the disease to prevent the spread and spread of the disease,100 billion/g Bacillus subtilis WP and 8%Ningnanmycin AS can be used as a rotation agent.Diseases are effectively controlled.3.Using the plate confrontation method,120 antagonistic strains were isolated from the soil of the resistant cotton to Fusarium wilt.The promote sprout analysis and pot experiments showed that KX-33antagonistic bacteria could obviously shorten the germination time and promote the growth of the cotton seedlings.The bud length,the root length and the bud fresh weight were 8.53 cm,5.40 cm and 1.72 g respectively.The control efficacy of pathogens DD64,DD89,DD11 and DD22 were 75.32%,72.77%,69.48%and 68.81%,which were significantly higher than those of other agents（P<0.05）.The antagonistic bacteria can grow normally under salt and alkali environment,and have certain salt and alkali resistance.Combined with the morphology,physiological and biochemical characteristics of the strain,16S r DNA and sequence analysis,the antagonistic bacterial strain KX-33 was detected as gram-positive bacteria,rod-shaped and spore,and has the highest homology with Bacillus pumilus（FJ763643.1）.