Effects of Cutting Size and Plant Growth Regulator on Rooting Ability of Cunninghamia lanceolata

Using 1 year newborn cuttings of Cunninghamia lanceolata as the experimental material, adopt three factors experiment design, including the cutting size, the types and consistency of hormones. Researching, the various factors and their interactions influence on C. lanceolata cuttings rooting index, and using the method of subordinate function to comprehensively evaluate the cuttings rooting effect of each handled processing combinations. Result showed that among the 3 main factors, the hormones types have the greatest influence on C. lanceolata cuttings rooting index, in addition, the influence on the number of adventitious roots have reached significant level, that influence on the other root indicators have reached very significant level; The effect of hormones concentration on C. lanceolata cuttings rooting index is slightly deficient, the influence on the other root indicators have reached very significant or significant level, except the longest adventitious root length and root diameter; Cutting size has the least influence on C. lanceolata cuttings rooting index, it has a very significant or significant influence on the small part of the rooting index. In all kinds of two-factor interaction, the interaction of hormone type × hormone concentration have the greatest influence on rooting index, that also has a very significant influence on rooting index except the aspect of root diamete; The interaction of cutting size × hormone type has less influence. The interaction of cutting size × hormone concentration has the least influence, which has a very significant or significant influence on small part of rooting index. Membership function comprehensive evaluation shows when cutting size is A₃ (diameter 4.00-5.49 mm, length 11.0 cm), hormone type is IBA, hormone concentration is 100 mg/kg, the maximum of average membership function value is 0.8815. The average membership function value 1.000 0 of rooting rate, decay rate and the longest adventitious roots length has the highest value in all combinations. The membership function value 0.923 7 of callus rate ranks second in all combinations. The rooting index's comprehensive performance of this combination is the best in all the combinations.