| Plant-parasitic nematodes are recognized as important pests,with at least 17 species,that seriously affect wheat.The most commonly recorded species of economic importance on wheat is cereal cyst nematode(Heterodera avenae,CCN),which has been detected in many countries,including Australia,India and et alibi.CCN was found initially in Hubei province,China,afterwards it was founded in major wheat areas in Beijing,Hebei,Henan, Anhui and et alibi,economic damage were reported in some areas.It is very urgent to know occurrence of CCN in Anhui province,for making measures for CCN control in this province.For those aims,we carried out plant nematode investigation of rhizophere of wheat distribution,CCN distribution investigation,and yield loss experiments caused by CCN in Anhui province.Soils were sampled in field by "Zig-zag" and etc.from 5 sites,including Xiaoxian,Fuyang, Bengbu and et alibi in Anhui province,migratory nematode were isolated by Baermann funnel method,the cysts were isolated by Fenwick & Oostenbriak method.Nematodes were observed and measured under microscope by de Man method.Check-plots were designed with soil-treated application of Temik against CCN as control before sowing,and growth index investigated at earlier stage of wheat,and yield loss and Pf/Pi were count to embody damages of affected wheat in Xiaoxian of Anhui province.The identification was conducted on plant-parasitic nematodes of wheat rhizosphere in Xiaoxian,Wuhe,Fuyang,Bengbu and Hefei of Anhui province.Shows:there are 4 species among 7 genera of plant-parasitic nematodes were identified around wheat rhizosphere. They are T.neorninimus,F.cylindricus,P.coffeae,H.avenae,Paratylenchus spp., Aphelenchoides spp.and Xiphinema spp..Among those nematodes,H.avenae is the important wheat-parasitic nematode in Xiaoxian,average white female densities is 0.32·g-1soil.P.coffeae is the important wheat-parasitic nematode in Fuyang,average female densities in soil is 0.22·g-1soil.The results of vertical distribution of wheat rhizosphere in 3 different types of soil in Anhui province.Show:the percentages of plant-parasitic nematodes are 46.5%in sandy soil,38.9%in mixed soil and 31.1%in silt soil.Nematodes congregated in depth of 100-200mm soil layers accounting for whole investigation 51.4%and 64.4%in respectively in sandy soil and mixed soil.Nematodes congregated depth of 0-100mm soil layers,accounting for 48.6%in silt soil. CCN was found in 14 investigation sites among 18 towns and one agricultural demonstration garden in Xiaoxian,accounting for 70.6%,CCN was found both in sandy soil and mixed soil.Results of egg densities of CCN investigation shows,average egg densities is 6.5 eggs/g soil,ranging from 0 to 42.8 eggs/g soil,statistic results indicate plane distribution of CCN followed cluster model in the wheat field in Wangtun village, at Dulou town,Xiaoxian county of Anhui province.During 2006-2007,CCN was detected both in sandy soil and mixed soil Huaibei,Suzhou and Bengbu among 53 wheat field soil samples collected from 23 countries in Anhui province,and egg densities range from 1.3 to 7.0 eggs/g soil,the highest is 17.0 eggs/g soil in Majing town,at Xiaoxian county. Check-plots were designed with Temik soil-treated against CCN before sowing,Wheat growth investigation indicates:significant reduction of growth index was found compared with Temik-control plots,fresh-weight of per wheat plant of Xinmail 2 and Wanmai50 was reduced by 23.3%and 22.5%(p=0.05) respectively,ear numbers was reduced by 25.9% and 11.1%(p=0.05) respectively during booting stage,and damages significantly varies among 3 varieties.Compared with Temik-control plots,wheat yield of Xuzhou8625, Xinmai12 and WanmaiS0 was reduced by 11.0%,1.4%and 18.0%(p=0.05) respectively, spike number of Xuzhou8625 and Wanmai50 was reduced by 21.5%and 13.9%(p=0.05) respectively,but CCN didn't cause significant damages on grain weigh and grain numbers per spike of wheat. |
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