The diploid chromosome number of Schlumbergera truncata and Schlumbergera × buckleyi, in individuals with different types of petal color, was determined using root tips. The use of 8-hydroxyquinolein 0.003 M at 36 ºC provided better chromosome separation. C-banding technique and Giemsa coloration allowed the karyological study of these species. Schlumbergera × buckleyi hybrid (light pink) species has 2n = 22 chromosomes with karyotype formula 16M + 6SM. Schlumbergera truncata with red, white, and pink petals and 2n = 22 chromosomes has karyotype formula identical to Schlumbergera × buckleyi, while the plant with yellowish flowers has 2n = 34 chromosomes. Chromosome classification was based on the centromeric index. In plants with white, red, pink and light pink petal color, the best time to obtain metaphases is during flowering. Schlumbergera truncata with yellowish flowers has two annual peaks of mitotic division. These results give us a better understanding of the biology of the genus Schlumbergera and aid in taxonomic classification where phenotypic characteristics alone are not reliable enough to classify plants of the same taxon.
Cactaceae; karyotype; chromosome numbers; C-banding
