Objective  This paper aims to study the effects of rhizosphere soil addition of different aged Chinese fir plantation on the growth of aseptic seedlings of it, and to provide a theoretical basis for the mycorrhizal seedlings of Chinese fir.

  Method  The aseptic seedlings of 4 months old Chinese fir were transplanted into aseptic substrate soil, and (150 ± 2) g of rhizosphere soil (RS1), middle-aged rhizosphere soil (RS2), near mature rhizosphere soil (RS3), mature rhizosphere soil (RS4) and over mature rhizosphere soil (RS5) were added near the roots of seedlings. The nutrient content, pH and spore density of arbuscular mycorrhizal fungi (AMF) in rhizosphere soil were measured before adding. The AMF colonization rate, nutrient content and pH of substrate soil, morphological index and biomass of Chinese fir seedlings were measured one year after transplanting.

  Result  There were differences in nutrient content, pH and AMF spore density in rhizosphere soil of Chinese fir plantation of different ages. The addition of AMF significantly promoted the colonization rate of Chinese fir seedlings. There was a significant positive correlation between AMF infection rate and AMF spore density in rhizosphere soil of the Chinese fir stand. The colonization rate showed the rule of RS5 > RS4 > RS3 > RS1 > RS2 > CK. The addition of rhizosphere soil also promoted the growth of seedlings, such as ground diameter, seedling height, root length, crown width, number of basal branches and biomass accumulation. The addition of RS5 was better than the other four types of rhizosphere soil.

  Conclusion  The rhizosphere soil of Chinese fir stand can be used as a fungicide adding to the seedling of Chinese fir, increasing the colonization rate of mycorrhizal roots, and promoting the high-quality growth of seedlings, which has a great practical value to the seedlings of Chinese fir and the application of mycorrhizal fungi in forestry.