Objective  Adventitious root induction is an important method for the propagation of superior clones of Cunninghamia lanceolata. Adventitious root induction in C. lanceolata tissue culture is affected by many factors. However, the key factors that play a leading role are still unclear. By comparing the influences of different culture conditions on the induction of C. lanceolata adventitious roots, this study aimed to find out the most suitable culture factors for C. lanceolata rooting, laying a foundation for subsequent experiments and studies.

  Method  Using C. lanceolata clone T-c22 as the experimental material, by changing the nutrient conditions, the types and concentrations of plant growth regulator (hormone), removing needle leaves from shoots, adding activated carbon to the medium, light conditions and different light quality and other different culture factors, and various indexes of C. lanceolata rooting were investigated and statistically analyzed, in order to study the influence of different culture factors and the interaction between different factors and light on the rooting of C. lanceolata.

  Result  (1) The results showed that compared with darkness, light significantly increased the plant height, rooting rate, average root number and average root length of C. lanceolata shoots, and significantly inhibited the fresh root mass of C. lanceolata. (2) Both white light and red light can increase the rooting rate of C. lanceolata, reaching 100%. White light can significantly increase the number of roots of C. lanceolata. Both red light and blue light can significantly reduce the root length of C. lanceolata. And they can significantly increase the plant height of plantlets of C. lanceolata. (3) Adding IBA and NAA single hormone significantly increased the plant height, average number of roots, average root length, root fresh mass and root dry mass of C. lanceolata. The interaction of light and a single hormone significantly increased the average root number and average root length. (4) The medium containing appropriate nutrients will significantly increase the rooting rate, number of roots, average root length, average fresh root mass and average root dry mass of C. lanceolata. The interaction of light and the nutrition significantly increased the plant height and average root length of C. lanceolata. (5) Removal of needles significantly increased the height of plantlets, the average root length and the average dry mass of roots.The interaction of light and removing needle leaves from shoots had no significant effect on the induction of adventitious roots of C. lanceolata. (6) Activated carbon significantly reduced the rooting rate, number of roots, fresh root mass and root dry mass of C. lanceolata plantlets. The interaction of activated carbon and light significantly reduced the rooting rate and average root length of C. lanceolata.

  Conclusion  In this study, the importance order of factors affecting rooting of T-c22 clones of C. lanceolata was as follows: nutrients > species and concentration of plant growth regulators > different light quality > light duration and the interaction between light and other factors > whether or not to remove needles and activated carbon. The optimal medium for rooting of T-c22 clone of C. lanceolata was 1/2MS + NAA 0.5 mg/L + IBA 0.5 mg/L. The optimal rooting conditions for C. lanceolata were the addition of appropriate nutrients, the appropriate concentration of plant growth regulator (NAA 0.5 mg/L), the removal of some needles and the treatment of red light (16 h/d).