Chromosomes studies of rose cultivars: application into selection process

Abstract Mitotic chromosome numbers were determined for 41 roses cv. Except an aneuploid cv. (Parador, 2n = 27), all were belonging to an euploid range 2n = 2x (14), 3x (21), 4x (28) or 5x (35). The most interesting fact is the large ploidy scale into a biological type and the large distribution of the triploid cytotype. Whatever the ploidy level of the parentage, it was possible to obtain a progeny in the most case. Nevertheless, the best success was reached in the crossing situations: parents with the same chromosome number, triploid female or tetraploid male. The successfull progeny from triploid female could be explained by an unequal separation of the chromosome during the meiosis.