Growth and physiological responses of potato plantlets (Solanum tuberosum L. cv. Cipanas) to NaCl-induced salinity stress under in vitro conditions

Potato (Solanum tuberosum L. cv. Cipanas) is a high-yielding cultivar; however, its cultivation is often limited by salinity stress in marginal lands, which adversely affects plant growth and development. This study aimed to evaluate the effects of different NaCl concentrations on the growth and physiological responses of in vitro-grown potato plantlets and to determine the maximum salinity level that could be tolerated. The experiment consisted of five NaCl concentrations (0, 0.25, 0.50, 0.75, and 1.00%) arranged in a completely randomized design. Quantitative data were analyzed using one-way analysis of variance (ANOVA), followed by Tukey's honestly significant difference (HSD) test at the 5% significance level. Increasing NaCl concentrations significantly reduced plantlet height, leaf number, and stomatal index, and induced progressive changes in plantlet color from green to yellowish-green and brownish-green. Potato plantlets remained tolerant to NaCl concentrations of 0.25% based on plantlet height and leaf number, whereas tolerance up to 0.50% was observed for plantlet color and stomatal index, with no significant differences compared with the control. These findings indicate that S. tuberosum L. cv. Cipanas exhibits moderate tolerance to NaCl-induced salinity under in vitro conditions.