In recent years, there has been growing interest in Tulipa tarda, a species belonging to the botanical tulip group, in the bulb plant market. This species is valuable as a bedding plant, mainly due to its multi-flowered stems and star-shaped, yellow flowers blooming in April, but also due to its ability to grow in one place for many years.

The low efficiency of traditional tulip propagation has led to the search for more effective in vitro propagation methods. The presented research focused on the formation of adventitious bulbs using methyl jasmonate (Me-JA) as a factor influencing micropropagation among ornamental geophytes.

The experiment used scales from adventitious bulbs obtained from an in vitro collection of T. tarda at the University of Agriculture, Kraków. The bulb scales (approx. 10 mm length, 4 mm width) were cultured in Petri dishes on MS solid medium containing 6% sucrose, 0-400 mg l^-1 Me-JA, and 0-0.5 mM 6-benzyl-aminopurine (BAP). After four weeks, Me-JA was removed from the medium. The cultures were maintained in the dark at 20°C.

After 12 weeks of culture, the presence of Me-JA alone in the medium reduced bulb formation. However, the combined application of 100 mg l^-1 Me-JA and 0.5 mM BAP enhanced the propagation efficiency (with 86% of explants forming bulbs) in comparison to the control (BAP treatment, with 70% of explants forming bulbs). Higher concentrations of Me-JA significantly reduced adventitious bulb regeneration, with only 38% of explants forming bulbs. An average of 1.2 adventitious bulbs per explant was obtained, which was not significantly higher than the control (1.1 bulbs per explant). All adventitious bulbs formed roots at a similar level (approx. 3 roots/bulb). The bulbs also began to develop leaves. The treatment with 100 mg l^-1 Me-JA and 0.5 µM BAP led to twice as many bulbs developing leaves (22%) compared with the control (10%).

In conclusion, the combined application of 100 mg l^-1 Me-JA and 0.5 mM BAP positively influenced adventitious bulbs regeneration and leaf development.

Future research should investigate the long-term viability of these bulbs and assess their performance under greenhouse or field conditions.