Study On Competitive Relationship Of Fusarium Graminearum Clade In Anhui

Fusarium head blight is a destructive disease which widespread occurrenced in warm,humid and semi-humid regions.Anhui,located in the north-south transition zone and which possesses suitable climatic conditions,is wheat scab retransmission and prone areas.Fusarium graminearum populations distribution in corn-wheat and rice-wheat rotation areas of Anhui Province was analyzed in this study.The relationship between population distribution and previous crops was analyzed,and on this basis,the viability,pathogenicity and competitive role on wheat and corn of Fusarium asiaticum and F.graminearum populations were comparatived.Additionally,competitiveness of Fg and Fa on corn stover and rice paddy mediums was studied.The results will provide a theoretical basis for the scientific control wheat scab.The main results obtained as follows:1.Fusarium graminearum populations distribution in corn-wheat and rice-wheat rotation areas of Anhui ProvinceAlong the corn-wheat and rice-wheat rotation transition zone in Anhui Province,10 sampling points were selected,which by multiple plots,large samples dispersion sampling method.Using tissue isolation and PCR-RFLP method,samples were isolated and identified.In the 300 isolates obtained,273 Fa strains detected with the detection rate of 91%;and 27 Fg strain detected with the detection rate was 9%.This result showed that the dominant populations of Fusarium graminearum in corn-wheat and rice-wheat transition from Anhui was Fa.There are some differences in population distribution of Fusarium graminearum.Fg average detection rate reached 21.1% in corn-wheat rotation area,which was higher than mixed planted area and rice-wheat rotation area.Yingshang and Fengtai,which were adjacent and posseses similar geographical environment,meteorological data of mid March to late April was similar.Because of these,the differences in population distribution was most likely caused by the difference of previous crop.2 Competitiveness of Fa and Fg flora in Anhui Fusarium graminearum2.1 Spore production: Spore production of Fuyang Sanshili town Fa,Fg,Yangzhuang in Yingshang Fa,Fg,Yingshang Shisanli Fa,Fg,Yingshang Xiaqiao Fa,Fg,Yingshang daizhuang village Fa,Fg Fengtai Guiji Fa,Fg were compared.The results showed that:Fg conidiation were higher than Fa,Fg strains in the corn-wheat rotation area produced most spores with an average of 2.03 × 106 / ml,and Fa strains in the mixed planted produced least spores an average of 8.07 × 105 cells / ml.2.2 Mycelial growth rate: Fg growth rate was generally higher than Fa in the tested strains;Fa,Fg in corn-wheat rotation region average growth rate is the largest,with2.395cm/d and 2.465cm/d,respectively.Fa,Fg in Rice-wheat rotation system isolates was smaller than other areas.2.3 Virulence: Artificial inoculation results showed there are some differences insix pairs of Fa and Fg.Virulence strains of Sanshili Fg in corn-wheat rotation area disease index was highest with 49%,Virulence strains shisanli Fa disease index was lowest with 34%,and Fg virulence generally higher than the Fa's.2.4 Competitive of Fa and Fg strains on wheatMixed spore virulence: the above six pairs of strains were mixed by 1: 3,3: 1,1: 1ratio,then spray-inoculated on wheat during flowering stage.The results showed that scab occurs relatively lighter when a higher proportion of Fa in 6 strains tested.In behalf of the village,for example,when using the ratio of 3: 1 inoculated,the disease index was only 25%;but at 1: 3 and 1: 1,the disease index were 47.5% and 42.5%.Fg detection rate after mixed inoculation : The spores produced on the incidence of wheat was washed,single spore separated and purificated.30 strains was selected and identified by PCR-RFLP method.The results showed that Fa and Fg were inoculated at a concentration of 3: 1,Fg detection rate of zero,Fa and Fg were inoculated at a concentration of 1: 3,Fg detection rate was highest.Effect of Rotation area of Fg detection rate: Fa and Fg mixed inoculated on wheat in corn-wheat rotation region,Fg was detected mostly;Fg could be detected with the detection rate was 1.7% only when Fa and Fg in rice-wheat rotation area only at a concentration of 1: 3 inoculated,and.Thus,in competitive of Fa and Fg strains,the dominant populations of Fusarium graminearum was Fa and Fg detection rate was likely caused by the difference of previous crop.3 Competitiveness of Fa and Fg on corn earMixed spore the two pairs of strains were mixed by 1: 1 ratio and inoculated corn by three ways of injection,gauze law and trauma.The results are as follows:3.1 Different inoculation methods on corn: Inoculation condition survey Two weeks later showed that The onset of the lighter on corn ear,where law and gauze wound inoculated,corn disease index were 20%;injection inoculation incidence of heavy ears of corn.3.2 Fg detection rate on corn:Mixed spore the two pairs of strains were mixed by 1: 1ratio inoculated middle and upper corn ear.The results showed that Fa detection rate of61.67%,Fg detection rate of 38.33%,which can be seen on the cob,Fa is competitive in Fg.4 Effect of different media on competitiveness of Fa and FgMixed spore the two pairs of strains were mixed by 1: 1 ratio inoculated corn stalk and rice straw until sporulation then single spore identification.The results show that Fa overall detection rate higher than the Fg,corn stalks Fg detection rate was higher rice straw.Competitiveness the number of perithecia produced of Fa and Fg on different medium.The results showed that the number per unit area of perithecia on corn stalk is much higher than rice straw;Fa quantity produced perithecia on both groups was higher than Fg's.