Karyotype variability of 12 Tulipa L. cultivars

Tulipa L. (Liliaceae) is one of the most prominent ornamental bulb crops worldwide, holding a central position in the ornamental horticultural industry. Tulipa cultivars are classified into 16 horticultural groups, based on morphology and flowering characteristics. The basic chromosome number in the genus Tulipa is x = 12. This study presents a comprehensive karyomorphometric analysis of 12 cultivated tulip cultivars of which 10 for the first time. Microphotographs of their karyotype and their karyotype formula are given. Further, indices about interchromosomal and intrachromosomal asymmetry are provided. The findings reveal that most cultivars were diploid, 2n = 24, namely “Danceline” (Double Late group), “Brest” (Fringed group); “White Triumphator” (Lily-flowered group); “Green Wave” (Parrot group); “White prince” (Single early group); “Queen of Night” (Single late group); “Ile de France”, “Negrita”, “Purple Flag” (Triumph Group) and “Virichic” (Viridiflora group). Two triploid cases 2n = 36, were identified; i.e., “Fostery King” and “Van Eijk”, consistent with the Darwin hybrid group, which predominantly comprises triploid members. The karyotype morphology aligned with previous research of the genus, showing a symmetrical structure with sub-metacentric and acrocentric chromosomes of similar sizes.