Paclobutrazol (PBZ) acts by inhibiting gibberellin biosynthesis, a plant hormone responsible for stem elongation and vegetative growth. This inhibition leads to reduced apical dominance and enhanced reproductive development. As a result, the plant allocates more assimilates toward flowering, pod formation, and grain filling rather than vegetative expansion. It also promotes higher chlorophyll content, improves photosynthetic efficiency, and strengthens the plant’s defense mechanism under stress conditions such as drought. The overall effect is compact growth, uniform maturity, and improved yield quality and quantity.