Abstract:

To explore the positive and negative effects of dazomet and chloropicrin on the replanted soil，the abundance of total nematode，community composition，biodiversity and ecological indices，and soil nutrient were used as the main evaluating indices in the greenhouse of strawberry. Based on those above indices and the Redundancy analysis（RDA），our study will provide references for the replanted soil of scientific management. Our result showed that the total number of nematode in replanted soil declined by 83.24% and 85.48% after applying dazomet and chloropicrin，respectively. But soil diversity index（H’）and maturity index（MI）had no significant change. The content of soil organic matter，available phosphorus and available potassium was also significantly reduced（68.33% and 50.00%，67.93% and 71.55%，50.36% and 56.20%，respectively）after the application of dazomet and chloropicrin. In addition，the value of pH rose to 7.69 and 7.68，respectively（the value of pH in the control soil was 7.27）. RDA analysis indicated that dazomet and chloropicrin had significantly positive correlations with Rhabditis，Aphelenchus nematodes，soil organic matter，available phosphorus，and available potassium. The result revealed that the number of harmful nematodes of Aphelenchus was reduced by 41.47% and 29.77%，and the number of beneficial nematodes of Rhabditis was significantly dropped about 10% under treatment of dazomet and chloropicrin，respectively. The main reason might be that，the two fumigants could strongly reduce the content of soil nutrient. It was suggested that dazomet and chloropicrin not only could effectively reduce the number of harmful nematodes，but also had negative effect on the beneficial nematodes and soil nutrient. In conclusion，the inhibition effect of dazomet on harmful nematodes was greater than chloropicrin，and the number of Eucephalobus belonging to bacterivores increased by 42.03% with dazomet treatment at the same time. Therefore，the negative effect of chloropicrin was greater and should be used carefully in production.

Key words: strawberry, soil nematode community, replanted, dazomet, chloropicrin, fertility