Hatching Characters And Optimization Of The Pathotype Bioassay For Heterodera Avenae Peixian Population From Jiangsu Province And Resistance Evaluation Of Wheat Cultivar

Cereal cyst nematode (CCN) is an important plant parasitic nematode on cereal crops and cause serious damage on wheat yield and quality in more than40countries worldwide. Since1989it was discovered in Hubei province, CCN has been distributed in13provinces (city or autonomous region) and threatens the security of wheat production in China. The discovery of CCN in Jiangsu Province in May,2009, made the urgent needs for understanding the hatching characters for second stage juveniles of CCN, the optimization of pathotype bioassay and screening wheat cultivars resistance to pathotype of Jiangsu populations. The study provided useful information for the integrated control of CCN.In lab condition, the hatching characters of Heterodera avenae from Peixian, Jiangsu Province were studied under the influence of temperature and time. The results showed that the hatching of seconde-stage juveniles from cysts was stimulated by cold temperature. The juveniles hatched at10,15and25℃after cysts pre-treated at5℃for8weeks. Duration of hatching lasted6weeks at10℃and it was the longest hatching time. Juveniles hatched the most at15℃and the cumulative hatching rate was43.2%; However, a few juveniles hatched at25℃and no juveniles at28℃and30℃. Duration of hatching lasted7weeks at5℃after cysts pre-treated at5℃for4weeks and it was also the longest hatching time. When the cysts pre-treated at5℃for14weeks was incubated at15℃, the juveniles hatched during one week interval was the highest with the number of322and the cumulative hatching rate was62%. Juvenile hatching was improved by the extension of cold pre-treated period.The number of white females of H. avenae produced on wheat seedlings was studied in the lab under the influences of container size and inoculums density of second stage juveniles, and the conditions of pathotype bioassay for cereal cyst nematodes (CCN) was optimized. The results showed that the number of white females produced on wheat seedling was significantly different in different inoculum densities. The white females produced on wheat seedlings were increasing with the increase of inoculum density under lower inoculums density. The wheat seedlings planted in different size of containers and inoculated with density of4juveniles per cm3soil produced the largest number of white females. With the same inoculum density,4juveniles per cm3soil, the size of PVC container wth3cm X15cm not only decreased the number of nematode inoculum, but also increased the evaluation accuracy for resistance/susceptible by differentiate hosts.In order to screen the resistant wheat cultivars to Heterodera avenae),40cultivars from5provinces were evaluated by two test methods of second juvenile inoculation under greenhouse and eggs inoculation under natural conditions and one field trial, with the nematode population from Peixian, Jiangsu province, China. The greenhouse test with juveniles revealed no cultivar was immune to H. avenae. However, cultivars Huamai No.1, Wenliang58and Yumai66-18were highly resistant, Yangmai13and Xumai7086were moderately resistant. Yannong5158was the most susceptible cultivar with average104.7white females per plant. In field trial, only Huamai No.1out of above mentioned resistant cultivars was evaluated as resistant. The sustainable test results demonstrated Huamai No.1can be used as the suggested resistant cultivar for planting in CCN heavily infested areas and as resistance resource for plant breeding. Because of the controlled conditions for nematodes inoculation and wheat growth, the resistance result evaluated by greenhouse test was more accurate compared with those from field trials. The results evaluated by eggs inoculation test were more variable when compared with those from juvenile test and field trial, therefore, it was demonstrated not suitable for the evaluation of wheat cultivars resistance to CCN.