| Orobanche cumana Wallr.is a holoparasitic plant parasite on the roots of sunflower that has serious impact on sunflower production.In this study,the pathogens isolated from the leaf blight of Orobanche cumana,F.oxysporum XXZ-9,F.solani XHZ1-7(F.solani)and F.equiseti YL-1(F.equiseti),were combined to form different combination The inhibition effects of different combination on the parasitic effects of Orobanche cumana on sunflower were studied under both laboratory and field experiments.The results were listed as follows:1.Three kinds of Fusarium spp.were combined into different combination groups namely,Combination 1: YL-1+XHZ1-7;Combination 2: XHZ1-7+XXZ-9;Combination 3:yl-1+xxz-9;Combination 4: YL-1+XXZ-9+XHZ1-7.The conidial solution was inoculated on the stem of Orobanche cumana using the acupuncture inoculation method,and the results showed that combination 4 showed the strongest pathogenicity,showing the average length of the diseased spot(2.88cm)at the stem inoculation site of Orobanche cumana.Combination 1 had the weakest pathogenicity,with the average length of the diseased spot recorded as 1.06 cm.The pathogenicity test result from the same combination on sunflower showed that the lengths of diseased spot formed on the stems of the four different combinations after inoculation and the water control treatment had no significant difference from the control setup.In the point tray experiment,the results showed that each treatment group had no typical symptoms of disease on sunflowers,and there was no significant difference in plant height as compared to the water control.However,there are certain differences in the impact of different combination on the number of nodules and stems parasitized by sunflower broomrape.Among them,combination 4 treatment has the greatest impact on the number of nodules and stems by sunflower broomrape.2.The antagonism and liquid co-culture experiments were conducted to verify whether the three isolates of Fusarium spp.had mutual antagonism.The results showed that the hyphae of the three isolates spread and grew mutually on PDA plate medium with no inhibition zone.The results of liquid co-culture experiments showed that after conidial solutions of the three different Fusarium spp.strains were inoculated into the mixed fermentation filtrates of the other two strains,the fermentation filtrates of the other two strains had a certain promoting effect on the mycelium growth of the inoculated strain except for YL-1 strain.However,the number of conidia of the inoculated strain was not significantly changed in the fermentation broth of different strains.However,they had a certain effect on the crude toxin secretion of the inoculated strains and was represented as the fermentation filtrate.The fermentation filtrate by XHZ1-7 promoted the crude toxin secretion of YL-1which was increased by 0.06 mg/m L.The fermentation filtrate obtained by XXZ-9 showed a certain inhibitory effect on the secretion of crude toxin from YL-1,and the secretion was reduced by 0.13 mg/m L.3.In the greenhouse,conidia liquid irrigation method was used to study the effects of different combination of Fusarium spp.on the number of nodules and stems parasitized by sunflower broomrape.The results showed that combination 4(YL-1+XXZ-9+XHZ1-7)had obvious inhibitory effects on the parasitism of sunflower,with 26.6 tubercles,respectively,which were 53.2 fewer than the control.The number of stems of O.cumana was 2.2,respectively,which was 10.2 less than that of the control.4.The control effect of the resistance inducer Jinmiao Target combinations and combination of Fusarium spp.isolated form the blight pathogen on broomrape was studied in different locations.The results showed that combinations could inhibit the parasitism of O.cumana.on sunflower(V6 stage).The results of treatment 3 in Guyang county of Baotou city showed that the parasitic rate and the parasitic intensity were 87.8% and 8.27%,respectively.As compared with the control,both parameters were decreased by 9.87% and1.58%,respectively.In terms of yield,different treatments in the two test sites could increase sunflower yield,but the increase in yield varied.Treatment 1 in Guyang County of Baotou city had the largest increase of 47.2%;Treatment 2 and Treatment 3 followed,with increases of 16.8% and 12.4%,respectively.Among the three treatments,Treatment 1 had the largest increase in yield of 54.2%,followed by Treatment 2 and Treatment 3,with an increase of33.4% and 52.4%,respectively.The results from the location in Hangjinqi,Ordos showed that the parasitic rates of three treatments,i.e.,30 m L/ mu of Jinmiao Target,80 m L/ mu of composite strain culture medium and 30 m L/ mu of Jinmiao Target+80 m L/ mu of composite strain culture medium,were 83.67%,87.33% and 85.67% respectively.Compared with the control,the parasitic rate is reduced by 13.1%,9.34% and 11.1%,respectively.The parasitic intensities were 15.5,20.11,and 16.15 with decreases of 10.34,5.73,and 9.69,respectively,as compared to the control.Regarding the yield of different treatments,Treatment 1 in Guyang County of Baotou City had the largest increase of 47.2%;Treatment 2 and Treatment3 followed,with increases of 16.8% and 12.4%,respectively.In terms of yield,Treatment 1had the highest increase in yield of 54.2%,followed by Treatment 2 and Treatment 3,with an increase of 33.4% and 52.4%,respectively. |
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