大豆胞囊线虫的休眠

以前研究发现,辽宁地区大豆生长期间及收获期土壤中胞囊孵出的二龄幼虫量很少,推测线虫卵的休眠与大豆生长时期或季节相关。为明确该地区大豆胞囊线虫的休眠特点,2002-2003年采用田间随机多点取样、室内分离及模拟自然条件孵化等方法对大豆胞囊线虫的休眠进行深入研究。结果表明:在生长季节,感病品种辽豆10根围土壤中的白色雌虫、卵囊及褐色的胞囊均可孵出二龄幼虫,且孵化持续时间较长,第21d仍有幼虫孵出,白色雌虫及卵囊内的卵孵化率高于褐色胞囊;不同作物对其根围土壤中胞囊内卵的孵化影响不大,寄主作物大豆、非寄主作物玉米根围及休闲地土壤中的胞囊在条件适宜均可孵出二龄幼虫;季节对胞囊内卵的孵化有较大的影响,出苗期孵化率最高,收获期最低,2周时平均1个胞囊孵出幼虫分别为83.8和9.7条;胞囊皮对线虫卵的孵化有显著的影响。表明沈阳地区大豆胞囊线虫在正常和逆境条件下均有部分卵表现休眠。

Dormancy of the soybean cyst nematode Heterodera glycines

Previous research in Liaoning suggested that few juveniles hatch from cysts collected during the soybean growing and harvest seasons, and indicated that dormancy of Heterodera glycines is related to the soybean growing stage or season. In order to determine the dormancy character of H.glycines in this area, an intensive study on dormancy of H.glycines was conducted from 2002-2003. Nematodes were collected from fields and hatched in vitro under conditions designed to model the natural environment. The results showed that second stage juveniles could hatch from H.glycines white females, egg sacs and brown cysts from soil collected from the soybean rhizosphere during the growing season. This duration of hatching was long; juveniles continued to hatch from eggs at 21 days. The hatch rate of eggs in white females and egg sacs was higher than that of eggs in brown cysts. The crop type had no great effect on hatching of eggs in cysts; the eggs in cysts from fallow fields and the corn and soybean rhizosphere soils could hatch in vitro when conditions were suitable. The rate of hatch of eggs in cysts fluctuated seasonally, with the greatest rate of hatch in May 12 (host seedling stage), and the lowest in October 12 (harvest), 83.8 and 9.7 juveniles per cyst hatching within 2 weeks, respectively. Presence of an intact cyst wall significantly influenced hatching. Results suggest that a portion of H.glycines eggs exhibit dormancy under normal and adverse conditions in the Liaoning Province.