| Cereal cyst nematode (CCN) is an important plant parasitic nematode in the world, which cause great damage to cereal crops, such as wheat, barley, rye, oats and pasture. It has been widely distributed in more than 40 countries all over the world. At present, CCN have been spread to 13 provinces in China. The better understanding of the distribution of CCN in Jiangsu Province, the species of Jiangsu populations, their phylogenetic relationship and chemical control, will provide valuable information for wheat production and food security in Jiangsu Province.During May of 2010, the investigation of CCN was carried out on 202 wheat fields from 166 villages of 40 counties in 8 districts located at northern and central part of Jiangsu Province, China. Total 113 samples with root s and soils were collected and 299 samples were collected by local plant protection stations. The extraction results demonstrated that 88 out of 113 and 278 out of 299 samples were detected with CCN, the incidence rate was 46.4% and 91.7%, the average population density was 12.1 and 25.2 cysts per 100 mL soil, respectively. The investigation revealed that the distribution of CCN in Jiangsu province was not uniform. CCN was widely distributed in districts of Xuzhou, Taizhou, Suqian and Yangzhou, and the incidence rates of CCN were low in districts of Nantong, Yancheng, Huai'an and Lianyungang. The average population density of samples from Xuzhou was highest with 23.2 cysts/100ml soil, for Huai' an and Suqian, with 22.7 and 21.3 cysts /100ml soil, respectively.The morphological and molecular characteristics were identified for 29 Jiangsu CCN populations. The morphometrics of 15 populations were measured for cyst, vulval cone and second stage juvenile. After comparison with the data described by Subbotin et al. (2003), Heterodera avenae was identified as the major species of cereal cyst nematode in Jiangsu Province. The ITS region of ribosomal DNA was amplified from 24 Jiangsu populations and the PCR product with the length of 1045 bp was obtained from all populations. After the purification and sequencing the PCR products, a phylogenetic tree was constructed based on the ITS sequences from Jiangsu populations and other species and populations. The phylogeny analysis revealed that all Jiangsu populations were grouped with the species from Heterodera avenae complex, which was one of the branches of the H. avenae group. Most of the Jiangsu populations were genetically closed to the Russian and German populations of H. pratensis.The control effects of 3 different usages from 5 granular nematicides (GR) with efficient components of aldicarb, carbofuran, cadusafos, fenamiphos and avermectin respectively, were evaluated on CCN in wheat field during regreening stage. The result showed the numbers of cysts in soil collected from different treatments were clearly dropped after nematicide application. However, there is no significant difference in revision cyst reduced rates between different nematicide treatments. The significant differences were demonstrated in wheat height, root weight, fresh plant weight between different treatments and their yields were increased when compared with the control. The revision cyst reduced rate of treatment with 30 kg/hm2 of 0.5% avermectin GR was the highest as 55.13% and wheat yield was increased 18.54% when compared with control. The treatment of 60kg/hm2 of 0.5% avermectin GR obtained the highest wheat growth as 59.32 cm when compared with those from other treatments. Due to the effects of 0.5% avermectin GR on inhibiting the nematode reproduction and improving the wheat growth, the usage of 30 kg/ hm2 was suggested to be applied in regreening field heavily infested with CCN, which might decrease the yield loss caused by CCN to some extent. |
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