<p>Polyploidy plays a critical role in driving diversification and adaptation in many plant species, affecting physiological, developmental, and morphological traits. Here, we explore genotype-specific responses to colchicine-induced polyploidy in coriander (<i>Coriandrum sativum L.</i>), shedding light on the fundamental changes in plant architecture and resource allocation. Three colchicine application methods—root immersion, seed soaking, and shoot apical meristem treatment—were tested across three genotypes. Shoot apical meristem treatment at colchicine concentrations of 0.3% and 0.5% achieved the highest polyploid induction efficiency, with 64.88% and 81.55% of plants showing successful tetraploid formation, respectively. In contrast, root immersion and seed soaking methods showed lower success rates, with significant plant mortality and reduced viability observed, particularly at higher colchicine concentrations. Flow cytometry and chromosome counting confirmed the stable induction of tetraploids, with genotype-specific variations in response to colchicine treatment. In tetraploid plants, larger stomata but reduced stomatal density and altered growth patterns were observed, reflecting key physiological adaptations linked to polyploidy. Despite trade-offs in plant height (-18%) and umbel number (-20%), tetraploidy resulted in increased seed size, seed weight, and total biomass per plant (biological yield), illustrating how polyploidy influences both morphological and reproductive strategies. These findings highlight genotype-specific morphological and physiological adaptations to colchicine-induced polyploidy, providing insights critical for breeding improved coriander varieties with targeted traits. By characterizing the morphological and physiological responses to induced tetraploidy, this research provides valuable insights into the polyploid plant adaptation and suggests potential avenues for integrating basic and applied approaches in plant breeding.</p>