The aim of the study is to investigate the effects of different retardant concentrations on the growth and development of Phalaenopsis hybrid protocorms in vitro, as well as to identify the anatomical and morphological features of leaves formed under various cultivation and storage conditions. The study was conducted from 2023 to 2025 in the Plant Biotechnology Laboratory of the N.V. Tsitsin Main Botanical Garden of the Russian Academy of Sciences. Phalaenopsis hybrid protocorms were obtained by asymbiotic seed sowing on Gamborg (1968) nutrient medium supplemented with 0.5 mg/L 6-benzylaminopurine (6-BAP). The effects of various retardants, their concentrations, and temperatures on the preservation of Phalaenopsis hybrid protocorms in vitro were studied. When protocorms were grown on Murashige-Skoog (1962) nutrient medium with a 2-fold reduction in the concentration of macrosalts (½MS) and the addition of chlorocholine chloride (CCC) at a concentration of 0.2–0.4 mg/L at a temperature of 15 °C after 18 months without transplantation, the viability level was 80–90 %. On ½ MS nutrient medium with the addition of 0.2 mg/L CCC, the proportion of seedling formation reached 90 %. The highest percentage of protocorm-like bodies (PLB) was observed in explants cultured on ½ MS with 0.4 mg/L CCC. Anatomical and morphological studies revealed plasticity in leaf structure under different temperature conditions. At 24 °C, leaves were characterized by a lower density of stomata, predominantly rounded in shape, and a more organized mesophyll structure. At 15 °C, the number of stomata was higher, the shape was elliptical, and the leaf mesophyll was less differentiated. The results of this study can serve as practical recommendations for the maintenance and propagation of Phalaenopsis hybrid in vitro.
Hussien et al. (Fri,) studied this question.