Screening suitable companion crops is an effective solution for vegetable continuous cropping
obstacle in greenhouse production．To explore the companion effect of cereal crops on tomato rhizosphere，we
monitored the responses of soil enzyme activities，microbial and root-knot nematodes in the root zone to tomato
companion with barley，wheat and rice using pot experiments．The results showed that the activities of soil
urease，protease and invertase were increased after companion growth with barley，wheat and rice for 30，40
and 50 days．In the intercropping of barley and wheat，rhizosphere bacteria and actinomycetes were significantly
increased while the fungi abundance was significantly decreased．The number of second-stage juveniles（J₂）
and egg density of Meloidogyne spp. in tomato rhizosphere was significantly lower than the control．Fifty days after
companion growth，the reduction rate of Mloidogyne spp. J₂ by barley，wheat and rice was 74.81%，42.64% and
45.74% respectively，while the loss rate of egg density was 51.29%，35.57% and 29.86% respectively．Taken
together，companion growth of cereal crops increased soil enzyme activities，improved the community composition
of soil microbes and suppressed invasion of root knot nematodes in tomato rhizosphere，among which barley is the
most promising companion crops in greenhouse tomato production．