连作年限对番茄根围土壤根结线虫二龄幼虫与自由生活线虫数量的影响

Influence of continuous tomato-cropping on second-stage juveniles of root-knot nematode and free-living nematodes from rhizosphere soil in plastic greenhouse

保护地连作是根结线虫为害严重的主要原因,为评估连作年限对根结线虫数量及其与土壤线虫数量关系,选择典型的不同连作时间的保护地(种植番茄),研究番茄生长期间根围土壤不同土层的根结线虫二龄幼虫(second-stage juveniles,J2)与自由生活线虫数量的动态变化。结果表明:根结线虫J2数量随连作年限增加而增多,0和5-year土壤中根结线虫数量少,平均根结线虫数为1.1和2.1条/100g干土,8、10和12-year土壤中根结线虫数量平均值分别为154.9、68.3和861.8条/100g干土;在0～30cm土层,根结线虫J2数量随土层加深而增加,主要分布在20～30cm土层。土壤自由生活线虫数量随土层的增加而增多,连作对自由生活线虫数量无显著影响。0和5-year土壤中根结线虫群体占土壤线虫总数的比例小,属稀有类群,在土壤线虫中处于稳定的群落结构状态。连作8、10和12-year的土壤中根结线虫J2为优势类群,土壤中自由生活线虫数量与根结线虫数量呈现相反的趋势,根结线虫J2占土壤线虫总数的比例增加,自由生活线虫与根结线虫J2数量的比值显著降低(P<0.05)。

Root-knot nematode （Meloidogyne sp.） is a destructive pest of vegetable and difficult to be ma-naged, especially in greenhouse of continuous planting tomato. For determining the influence of continuous planting on soil nematodes, the dynamics of second-stage juveniles （RKN J2） of root-knot nematode and free-living nematode in rhizosphere soil were investigated during the tomato growing season. The individuals of RKN J2 increased with the longer planting years. The number of J2 at 0~30 cm in 0 and 5-year soil was significantly less than that of other tested soil （P〈0.05）, the average means were 1.1 and 2.1 per 100 g dry soil. While in 8, 10 and 12-year soil, J2 were 154.9, 68.3 and 861.8 per 100 g dry soil, respectively. The population of J2 increased with soil depth, and mainly distributed in 20~30 cm soil layer. The number of free-living nematode also increased with depth of soil. There was no relationship between the time of con-tinuous cropping and the number of soil free living nematode. The percentage of RKN J2 in total soil nematode was lower in 0 and 5-year, Meloidogyne sp. was the rare group and kept relative stable population structure with the other soil nematodes. However, RKN J2 in 8, 10 and 12-year soil was the dominant group. The adverse trend was found between the number of free living nematode and RKN J2, the proportion of RKN J2 in total soil nematode increased with the time of continuous planting, and the ratio of free-living nematodes to RKN J2 decreased significantly （P〈0.05）.