Relationships between floral morphology, breeding behavior, and flower longevity in easter cactus

Abstract

The effects of floral morphology and breeding behavior on flower longevity were investigated in Easter cactus [Hatiora xgraeseri (Werderm.) Barthlott)]. Four clones were studied: two diploid (n = 11) clones ('Evita' and 'Purple Pride') that were highly self-incompatible (SI), and two cytochimeras (diploid epidermis and tetraploid subepidermis) that were recovered from the diploid cultivars, both of which were self-compatible (SC). The clones exhibited differences in the stage of floral development in which autogamy commenced. Autogamy commenced on the day of anthesis in the two 'Evita' clones and occurred ≃5 days after anthesis in the 'Purple Pride' cytochimera. In the 'Purple Pride' diploid clone, anthers and stigmatic lobes remained spatially separated during the period from anthesis to senescence. Examination of styles collected from senesced, undisturbed flowers showed that few pollen tubes traversed to the base of the styles for the two SI diploid clones, whereas large numbers of pollen tubes were present at the base of the styles for the two SC cytochimeras. Flower longevity for the 'Evita' cytochimera was significantly less than for 'Evita' diploid, but the diploid and cytochimeral clones of 'Purple Pride' exhibited similar flower longevities. Application of 2 mM silver thiosulfate, an inhibitor of ethylene (C2H4) action, did not affect flower longevity of 'Evita' cytochimera. Our results show that flower longevity in Easter cactus is influenced by breeding behavior and the Stage of floral development at which autogamy commences.