Effects of Atonik Application on the Growth of Kepok Banana (Musa × paradisiaca L.) Plantlets under In Vitro Drought Stress

Kepok banana (Musa × paradisiaca L.) is a local banana cultivar with considerable potential for cultivation; however, its productivity is often constrained by drought stress. Tissue culture provides an effective approach for producing uniform and disease-free planting materials, although plantlet growth may be adversely affected under water-deficit conditions. The application of Atonik, a plant growth regulator, has been proposed to improve plant growth under abiotic stress. This study aimed to evaluate the effects of Atonik concentration and immersion duration on the growth of Kepok banana plantlets under in vitro drought stress conditions induced by polyethylene glycol (PEG) 6000. The experiment was arranged in a factorial Completely Randomized Design (CRD) consisting of two factors. The first factor was Atonik concentration (0-, 3-, and 6-mL L⁻¹), while the second factor was immersion duration (0, 10, and 20 min). The treatments were combined into nine treatment combinations with three replications, resulting in 27 experimental units. Growth responses were evaluated based on plantlet height, root length, and chlorophyll content. Data were analyzed using analysis of variance (ANOVA), followed by Tukey’s HSD test at the 5% significance level. The results showed that the interaction between Atonik concentration and immersion duration significantly affected plantlet height. The highest plantlet height was recorded in treatment K1P3 (0 mL L⁻¹ Atonik with a 20-min immersion duration), while treatment K2P2 (3 mL L⁻¹ Atonik with a 10-min immersion duration) also exhibited favorable growth performance. However, Atonik application did not significantly affect root length or chlorophyll content under PEG-induced drought stress conditions. Overall, the effectiveness of Atonik in improving the growth and physiological characteristics of Kepok banana plantlets under in vitro drought stress conditions was limited and depended on the growth parameter evaluated.