Effects of Different Substrates and Growth Regulators on Rooting and Growth of Melliodendron xylocarpum Cuttings

To investigate the effects of different substrate compositions and plant growth regulators on the rooting and seedling growth of Melliodendron xylocarpum hardwood cuttings, a four-factor, three-level orthogonal experimental design was conducted. The study systematically analyzed the effects of substrate composition, type and concentration of growth regulators, and treatment duration on root morphology, and seedling growth. The results demonstrated that a vermiculite: perlite (3∶1) substrate promoted root diameter thickening but inhibited vertical growth, whereas a river sand: vermiculite (1∶1) mixture enhanced specific root length, shoot elongation, and biomass accumulation. Pure vermiculite significantly improved root number and surface area (P<0.05). Among growth regulators, IAA treatment effectively enhanced rooting percentage and specific root length. A concentration of 500 mg/L significantly increased rooting rate and aboveground biomass (P<0.05). A 30-minute treatment duration yielded the most favorable outcomes across multiple parameters. Range analysis indicated that growth regulator concentration exerted the greatest influence on overall performance, followed by treatment duration, substrate composition, and growth regulator type. Comprehensive evaluation showed that treatment T₆ achieved a 100% rooting rate and the best root quality and seedling growth performance, with the highest membership function value (0.73). Treatments T₈ and T₁₄ ranked second and third, respectively, while T₉ was the least effective. This study provides theoretical and technical support for optimizing the cutting propagation techniques of Melliodendron xylocarpum.