The effects of arbuscular mycorrhizal fungi and root interaction on the competition between and .

Understanding the factors that alter competitive interactions and coexistence between plants is a key issue in ecological research. A pot experiment was conducted to test the effects of root interaction and arbuscular mycorrhizal fungi (AMF) inoculation on the interspecies competition between and under different proportions of mixed sowing by the combination treatment of two levels of AMF inoculation (inoculation and non-inoculation) and two levels of root interaction (root interaction and non-root interaction). Overall, the aboveground and belowground biomass of and were not altered by AMF inoculation across planting ratios, probably because the fertile soil reduced the positive effect of AMF on plant growth. Both inter- and intraspecies root interaction significantly decreased the aboveground biomass of , but tended to increase the aboveground biomass of across planting ratios, and thus peaked at the 4:4 polyculture. These results showed that competed poorly with because of inter and intraspecies root interaction. Our results indicate that interspecies root interaction regulates the competitive ability of grass and legume in mixtures and further makes great contribution for overyielding. Furthermore, AMF may not be involved in plant-plant interaction in fertile condition.