Amina Ameen Kassab Bashi, Bashar Zeki Kassab Bashi, Hussien Jawad AL-Bayati
Background: The propagation of potato (Solanum tuberosum L.) through tissue culture provides a rapid and reliable means of producing disease-free plantlets for commercial cultivation. The efficiency of this process largely depends on the type and concentration of growth regulators used during different developmental stages. This study aimed to develop an optimized tissue culture protocol for potato cv. Arizona Class A by evaluating the effects of BA, Zeatin, and IBA across initiation, multiplication, rooting, and minitubers formation stages. Methods: Murashige and Skoog (MS) medium was supplemented with different concentrations of BA, Zeatin and IBA to determine their effects on shoot initiation, multiplication, rooting, and minituberization. Shoot number, root formation, and minituber production were recorded at each stage to identify the most effective hormonal combinations for in vitro propagation and subsequent greenhouse growth. Result: The addition of 1.0 mg L-1 BA to the MS medium resulted in the highest mean number of shoots (4.5 shoots explant-1) during initiation, while 2.0 mg L-1 BA significantly enhanced multiplication (17.2 shoots explant-1). Zeatin at 0.5 mg L-1 produced the best response in shoot number during initiation (2.0 shoots explant-1), whereas 0.75 mg L-1 Zeatin yielded the highest multiplication response (5.3 shoots explant-1). Rooting percentage reached its maximum (90%) with 0.5 mg L-1 IBA and concentrations between 0.5 and 0.75 mg L-1 significantly increased root number and length. During the minituberization stage under greenhouse conditions, plantlets derived from BA at 0.5 mg L-1 produced the highest number of minitubers, while Zeatin at 0.75 mg L-1 also promoted strong minitubers formation. These results highlight the crucial role of growth regulator selection at each developmental stage, with BA showing high efficiency during multiplication and minituberization, and Zeatin demonstrating moderate effects on multiplication but good potential in minitubers formation.