Abstract:

【Objective】 Dynamic distribution and developmental process of race 4 of Heterodera glycines (soybean cyst nematode, SCN) in the soybean root were monitored under field conditions in Shandong province during 2007 and 2008 in order to determine the developmental process and distribution of nematodes in soybean root, and provide information for effectively controlling the disease. 【Method】 The root systems were collected with mesh bag method and nematodes in root were stained by the method of fuchsin acid–NaCIO. The nematodes (including different stage juveniles) were counted under stereo microscope. 【Result】 The results of two years indicated that Np (nematodes per cm root) showed the similar sigmoid curve during 37 days of seedling age. The dynamic of development of the second-stage juveniles (J2), the third-stage juveniles (J3) and the fourth-stage juveniles (J4) were similar during the period of the experiment. The highest value of nematode density appeared at 4-5 weeks after soybean seedling emergence. All stage juveniles were distributed at different soil layers but mainly at 5-15 cm soil layer and J2 was the dominant population in each soil layer. 【Conclusion】 Under the average soil temperature around 20-22.2℃ in Shandong province, the first generation of SCN was finished at 22-35 days after soybean seedling emergence and the mature female was found at 22 days. From the results, the chemicals were suggested to be applied on the soil depths of 5-15 cm and lasted for 1 month after soybean seedling emergence and therefore to obtain the effective control of the nematodes..

Key words: Heterodera glycines')">Heterodera glycines, soybean root, dynamic distribution, developmental process