In Vitro Evaluation of Drought Tolerance in Malus Species Using PEG-Induced Osmotic

¹ Department of Agrotechnology, Faculty of Agriculture, University of Muhammadiyah, Jakarta, Indonesia
² Department of Horticulture, Faculty of Agriculture, Erciyes University, Kayseri, Turkiye

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Drought stress is one of the major abiotic factors limiting apple productivity, particularly in regions with increasing water scarcity. This study aimed to evaluate the drought tolerance of four apple species (Malus kirghisorum, Malus niedzwetzkyna, Malus sieversii, and Malus domestica) using an in vitro tissue culture approach. Shoot explants were cultured on a modified Murashige and Skoog (MS) medium supplemented with polyethylene glycol (PEG) 60 g/L, sucrose 30 g/L, agar 6 g, and plant growth regulators GA₃ and IBA (1 mg/L each). PEG was applied as an osmotic agent to simulate drought conditions, while control explants were maintained on PEG-free medium. After 45 days of culture, morphological parameters were assessed, including plant height, stem diameter, leaf number and size, fresh and dry biomass of shoots and roots, root length, and tissue damage scale. Results revealed significant interspecific variation in response to PEG-induced osmotic stress. M. sieversii and M. kirghisorum maintained higher root growth and biomass stability, indicating superior drought tolerance, whereas M. domestica and Malus niedzwetzkyana exhibited reduced growth and higher tissue damage, suggesting greater sensitivity. These findings confirm the existence of genetic variability in drought response among Malus species. The identified tolerant genotypes represent valuable genetic resources for breeding programs aimed at developing apple cultivars adapted to water-limited environments, thereby contributing to sustainable horticultural production under climate change scenarios.