Effects of Indole-3-Butyric Acid Application on Rooting and Vegetative Development in Hardwood Cuttings of Pterocarya fraxinifolia (Poiret) Spach

Abstract

Effects of different concentrations of indole-3-butyric acid (IBA) were studied relative to the rooting success, morphological development, and biomass characteristics of hardwood cuttings of Pterocarya fraxinifolia (Poiret) Spach collected from Diizce, Tiirkiye. Using a factorial design involving two cutting thickness classes and six IBA concentrations, the rooting percentage, number of roots per rooted cutting, shoot length, shoot diameter, number of shoots, fresh and dry shoot weight, and fresh and dry root weights were analyzed. The interaction between IBA concentration and cutting thickness played an important role in the vegetative propagation of Pterocatya fraxinifolia cuttings, especially in terms of rooting success, morphological characteristics, and biomass development. In particular, 1000 ppm and 2000 ppm IBA treatments yielded the most balanced and effective results in terms of rooting, shoot and root development, and biomass production. Although the 8000-ppm dose increased shoot biomass, it suppressed root development, indicating a potential phytotoxic effect at high concentrations. Principal component analysis also supported these findings and showed that 1000 ppm and 2000 ppm IBA doses provided homogeneous and healthy development. The results obtained emphasize that the optimal IBA dose should be carefully selected for the sustainable vegetative propagation; especially applications in the range of 1000 to 2000 ppm can provide important contributions to the propagation and conservation of the species.