In vitro germination and micropropagation of the Balkan endemic Lilium chalcedonicum L., a potential ornamental lily

Abstract

Lilium chalcedonicum L., a bulbous perennial endemic to the Balkans, is recognized for its considerable ornamental potential. In this study, seeds were gathered from a wild population and subjected to surface disinfection. Subsequently, they were placed in Petri dishes containing a half-strength Murashige and Skoog (MS) nutrient substrate (MS/2), with temperature conditions at 15 °C and 20 °C, followed by cycles of 5 °C and return to 15 °C and 20 °C, respectively. The in vitro-cultivated seedlings were then transplanted for further growth in MS medium enriched with either 30 g L-1 or 60 g L-1 sucrose and 0.1 mg L-1 6-N-benzyladenine (BA). In the following stage, the resulting bulblets were separated and cultivated in MS/2, either without hormones (Hf) or with BA at concentrations of 0.2 mg L-1, 0.5 mg L-1, or 1 mg L-1. Moreover, the combined influence of 1-naphthaleneacetic acid (NAA) at a concentration of 1.0 mg L-1 and 0.2 mg L-1 BA was examined. This stage was succeeded by a further division of the bulblets, and the explants were cultured in Hf, MS/2 or with the inclusion of 0.5 mg L-1 BA or a combination of BA and NAA at ratios of 0.2/1 and 0.5/0.05 mg L-1; zeatin at 0.5 mg L-1 was also used, combined with 0.05 mg L-1 NAA. Notably, all seeds exhibited a 100% germination rate following alternating temperature regimes including periods of low temperature. During the initial cultivation phase, each seedling gave rise to two bulblets measuring 0.6 cm in diameter. Subsequent subcultures on Hf substrates and those containing BA without NAA, resulted in the highest number of bulblets (1.6-2.2 bulbs/plant) of the largest diameter (0.8-0.9 cm). Particularly noteworthy was the substantial increase in the average number of produced bulblets during the subsequent subcultures (multiplication stage), where 16.9 bulbs were formed in MS/2 medium containing 0.5 mg L-1 BA, with a median diameter of 1.7 cm.