Infection Characteristics, Morphology Identification And Cultivar Resistance Of Cereal Cyst Nematode In Shandong

Cereal cyst nematode (CCN) was investigated in Shandong province in 2008, 2009 and 2010, 269 samples were collected from wheat roots and rhizosphere soils in 6 regional cities. CCN was also investigated using five-point method in typical susceptible wheat field. Cysts were extracted from soil samples from the wheat field in Binzhou. Cysts, eggs and second-stage juveniles (J2) were photographed and examined. Morphological observation of the cyst, vulval cone, eggs and J2 are described in this paper. In order to learn information about the developmental process and dynamics of CCN (Heterodera avena) juveniles in the root, nematodes in wheat root (variety Jimai 22 and Tainong 18) were recorded with interval times in 2009 and 2010. The root systems were collected with mesh bag method and nematodes in the root were stained by the method of acid fuchsin-NaCIO. The cereal cyst nematodes (including different stage juveniles) were counted under stereo microscope. Meanwhile, resistance against Heterodera avena was identified in 31 wheat lines. The results were showed as follows:1. Occurrence of cereal cyst nematodes in Shandong province and its distribution in susceptible wheat field.CCN were found in 11 counties/districts under the 6 regional cities of Binzhou, Jinan, Dezhou, Heze, Taian and Zaozhuang in Shandong. Occurrence of CCN is 36. 4% in this study. the cyst was not detected in Shanting and Taierzhuang districts of Zaozhuang city. CCN occurrence showed significant different in different regions. There were higher cyst density in Dawenkou and Hutun town in Taian city than other investigated area. Horizontal distribution of CCN in susceptible wheat field was not uniformity; more cysts were found in the middle of inter-row and planting row than other sampling point. Meanwhile, The abundances of CCN in four soil layers (0~10, 10~20, 20~30, and 30~40 cm) were analyzed. The greatest densities of CCN often occurred at of 0~30 cm depths, and then in 30~40 cm soil. The total number of CCN decreased with increasing of soil depth.2. Observations and morphometrics of cereal cyst nematode from Binzhou, Shandong:Morphological observation of the cyst, vulval cone, eggs and J2 are described in this paper. The species was determined to be Heterodera avenae characterized by J2 with body length 532±21μm(480~577), body width of 20.3±1.2μm (18.3~24.6), style length of 21.8±1.0μm (18.4~24.0) with well-developed style knobs, dorsal oesophageal gland orifice 5.2±1.8μm(2.4~8.6) from base of stylet, tail 64.8±4.1μm(54.6~73.1), hyaline tail terminal 38.9±2.7μm(33.4~45.7) and cysts were lemon-shaped, brown to dark brown, with protruding longer neck and vulva. A pair of semifenestra on vulval cone vulval underbridge absent, many bullae present obviously, vulval silt 8.8±1.5μm (7.0~11.6).3. Development and dynamics of cereal cyst nematode during wheat growing seasonCCN (Heterodera avenae) could invade the roots of 2 tested winter cultivars and complete its development under Shandong province climatic conditions. J2 was not detected in the root of 2 tested variety after seedling emergence (autumn season), J2 can invade root in January 15 (WP), but arrested development before February. With the increase of soil temperature, J2 density significantly increased in green stage of wheat growth (GS). J3 and J4 were detected in setting stage (SS) and heading stage (HS). There was only one generation per year in Shandong and the nematode completed its life cycle in mature stage of wheat. There was no significant difference in the number of nematodes per g fresh root between 2 tested variety Jimai 22 and Tainong 18 (p>0.05). Furthermore, Pratylenchus spp. was also detected in wheat root and rhizosphere. The coordinated damage of Pratylenchus spp. with Heterodera avena on the winter wheat should be attention.4. Identification of wheat variety resistance to Heterodera avenaeThere were no resistance variety to Heterodera avenae among tested wheat variety (line)., most cultivars were high susceptable (HS). Only Zimai 12 and Shannong 8355 were moderately susceptible (MS), 11~20 cysts/root, 6.5% of total tested variety (line),. Other 29 variety (line) were all high susceptable (HS), more than 20 cysts/root, 93.6% of total tested variety (line). In the present study, there was no relative between growth character of wheat root and numbers of new cysts under the same inoculation number of J2 .