Abstract: Extraction efficiency of soil nematodes by density (sucrose) centrifugation,modified Baermann funnel and shallow dish methods was compared.The total numbers of nematodes extracted by centrifugation method were 61 and 114 times higher than those by Baermann funnel and shallow dish methods,respectively.Nematodes of body size more than 53 μm(>300 mesh) and between 53 μm and 40 μm (300～400 mesh) extracted by centrifugation method were also significantly higher than those by Baermann funnel and shallow dish methods.In addition,centrifugation method was more effective for the extraction of all functional groups of nematodes (including bacterial-feeding,fungal-feeding,plant-feeding and omnivorous nematodes) than Baermann funnel and shallow dish methods.Baermann funnel method showed higher extraction efficiency than shallow dish method,and the difference was reflected in the numbers of bacterial-feeding nematodes and the nematodes with body size between 40 μm and 32 μm (400～500 mesh).However,shallow dish method was faster than Baermann funnel method when reaching similar relative extraction efficiency.

Key words: Cucumber, Light intensity, Excess Mn, Photosynthesis, Chlorophyll fluorescence