<i>In vitro</i>chromosome-doubling in tulip (<i>Tulipa gesneriana</i>L.)

Abstract

SummaryMost current tulip cultivars are diploid (2n = 24), some are triploid (Darwin Hybrids) and there are some rare tetraploid cultivars. Crosses between diploids are generally successful, but crosses between diploid cultivars and tetraploid selected species often fail, which constitutes a major obstacle to broadening of the genetic base. Our objective was thus to develop a method to obtain tetraploid material from diploid genotypes using a stem-disc regeneration process and the chromosome-doubling agent oryzalin, applied in different ways. Tetraploid clones were obtained from all treatments and from all cultivars tested. The final yield of tetraploids was low (0 – 3.75 tetraploids for one treated flower stem), but was sufficient to initiate crossing experiments between diploid and tetraploid progenitors to obtain triploid offspring.A genotypic effect was observed during the regeneration process.The cultivars ‘Lucky Strike’ and ‘Gander’ were more responsive in vitro than cvs. ‘Lustige Witwe’ and ‘Don Quichotte’. However, the percentage of tetraploid clones finally obtained was not influenced by genotype or by the way in which oryzalin was applied.