| Cereal cyst nematodes(CCN)is an important parasitic-nematode group that damage global crops such as wheat,barley and oat,among which Heterodera filipjevi and Heterodera avenae are the most economically important species and threaten the wheat production in China seriously.In this paper,the occurence of CCN on wheat in the main growing areas of Henan Province was investigated and the species of CCNs were quickly identified using duplex-PCR technique.The chemotaxis characteristics of second-stage juveniles(J2s)of H.filipjevi and H.avenae to the root of different wheat cultivars were observed using Plutonic F-127 gel as the medium and their possible pathogenic mechanisms were discussed.The control effects of four kinds of seed-coating formulations on CCN was evaluated under the field condition in order to provide guidance for the layout of wheat cultivars and the intergrated management of CCN.The results are as following:During the filling stage of wheat in May of year 2014 and 2015,a total of 61 root and soil samples of CCN were collected from 19 counties of eight districts,including Shangqiu,Luohe,Xuchang,Xinxiang,Hebi,Anyang,Puyang and Jiaozuo in Henan Province.The cyst densities of samples collected from districts of Shangqiu,Xinxiang,Hebi,Anyang and Puyang were higher and the occurrence of CCN were severer than those from other three districts.The species of CCN samples was rapidly identified using the duplex-PCR technique.The detection revealed that 33 samples were collected from wheat field solely infected with H.avenae,9 samples solely infected with H.filipjevi,and 19 samples co-infected with H.filipjevi and H.avenae.H.filipjevi was mainly occurred at Shangqiu,Luohe,Xuchang,Xinxiang and Jiaozuo districts and was the most common CCN species in Shangqiu area.Eight wheat cultivars including 'Huamai No.1','Aizaoba','Xumai 99','Huamai No.4','Xinmai No.19','Pumai No.9','Aikang 58' and 'Zhengmai 9023' were selected and the attraction of their root tips to H.filipjevi and H.avenae J2s was observed at different time using the Plutonic-127 gel as a medium.The results showed that the chemotaxis ability of H.filipjevi and H.avenae J2s to root tips of highly resistant 'Huamai No.1' and 'Aizaoba'were weak,however,to root tips of highly susceptible 'Aikang 58' and 'Zhengmai 9023'were strong.The number of H.filipjevi J2s gathered around the root tip of 'Zhengmai 9023'was obviously higher than that of H.avenae,and there were no significant differences between the numbers of H.filipjevi and H.avenae J2s gathered around the root tips of other cultivars.It is suggested that the chemotaxis variability of H.filipjevi and H.avenae J2s to wheat cultivars having different resistant levels to CCN which maybe related to the component of root exudates.The effects of four seed-coating formulations,including 2.5%fludioxoni(Fludionil),30%thiamethoxam(Crusier),27%difenoconazol-fludioxoni-thiamethoxam(Helix XTra)and 15%carbofuran-triadimefon thiram,were evaluated on controlling CCN in wheat field of Jiangsu Province.The results showed that the treatments with different concentrations of four formulations not only promoted the growth of wheat seedlings,but also inhibited the infection of J2s to wheat root.The inhibitory effects of 27%difenoconazol-fludioxoni-thiamethoxam and 15%carbofuran triadimefon-thiram on J2 infection were significantly higher than that of 2.5%fludioxoni and 30%thiamethoxam.Compared with the treatments of the other three kinds of formulations and 0.5%avermectin granular,the treatments of 27%difenoconazol-fludioxoni-thiamethoxam showed the better effects on CCN control and increased the wheat yield up to 22.02%.As a kind of low toxically and highly efficient seed coating formulation,27%difenoconazol-fludioxoni-thiamethoxam can be applied in the field for CCN control in the future,which may provide the technical support for integrated management of CCN on wheat in China. |
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