Auxin

Auxin is a class of plant hormones that regulate growth, development, and directional responses in cannabis and other plants. In cannabis breeding and cultivation, auxins influence stem elongation, root development, and apical dominance—the tendency of the main central stem to grow taller than lateral branches. Breeders and cultivators often monitor auxin distribution to understand plant architecture, as auxin levels affect whether a plant develops a tall, columnar structure or a more branching, bushy phenotype. Synthetic auxins are sometimes used in propagation to encourage root formation in cuttings, though naturally occurring auxin production is the primary driver of plant form in seed-grown and mature plants. Understanding auxin physiology is foundational to predictive breeding for desired plant structure and yield distribution.

Breeders select for auxin-responsive traits to control plant morphology—favoring either vigorous apical dominance for single-stem cultivation or suppressed apical dominance for multi-bud canopy development. Auxin sensitivity also influences internode spacing and branching angle, both critical architectural traits in commercial and breeding programs.