辽宁果树根围土壤线虫的多样性研究

Diversity of soil nematodes in orchards in Liaoning province

对辽宁沈阳、海城和旅顺3个地区4种果树根围土壤进行线虫种群多样性的研究,共鉴定出土壤线虫16科26个属,其中食细菌线虫营养类群为根围土壤中的优势类群,相对丰度均超过50%,植物寄生线虫类群次之,食真菌线虫类群数量较少,杂食—捕食性线虫类群数量最少。不同果树根围土壤中的线虫优势属各不相同。调查的果园在0～60cm土层都有土壤线虫的分布,但主要以20～30cm土层的土壤线虫总量为最多。土壤线虫的消长动态与果树根系的生长发育活动一致,在每年8—9月份果实膨大期线虫的繁殖数量达到最大。对不同果树根围线虫的生态指数分析表明,在树龄较小的果树根围,线虫群落的多样性指数和均匀度指数均高于树龄较高的果树,而优势度指数正相反;同时在树龄较小的果树根围鉴定到短体线虫属和矮化线虫属等植物病原线虫,而高龄树则无,说明植物线虫更易于侵袭幼龄果树,树龄较小的果树能够为比较多的线虫种类的繁殖提供营养。

The soil samples were collected from rhizosphere of four kinds of fruit trees in Shenyang, Haicheng and Lvshun cities of Liaoning province. Their diversities of nematode populations were studied and total 16 nematode families with 26 genera were identified under the microscope. The results showed that the bacterivore group was the dominant group with the proportion to the total nematode higher than 50% in all soil samples. The phytoparasitic feeders was the second dominant group. The numbers of fungivore and omnivore-predator feeders were lower than those of the former two groups. The dominant nematode genus was different in soils around different fruit trees. The nematodes were distributed in vertical soil depth of 0- 60cm and the nematode number was the highest in 20-30 cm soil depth compared with the other soil depths. The spatial and time dynamics of soil nematodes in orchard were consistent with the root growth of plant. The nematode number was the largest during the fruit enlargement period from August to September every year. Diversity and evenness of the nematode community under young trees were both higher than that of older trees, however, the index of dominance was opposite. The plant parasitic nematodes Pratylenchus and Tylenchorhynchus were found under young trees but not under old trees. The resuits demonstrated that the plant parasitic nematodes more easily infected young trees and the young tree was able to support more nematode populations.