Micropropagation of Ixia hybrids in liquid medium

Abstract

Ixia is a monocotyledonous bulbous plant native of the South African Cape Region grown commercially as an ornamental plant for the production of flower stems. Commercial propagation is by the vegetative production of corms, which may suffer from a number of serious phytosanitary problems. In order to increase production uniformity and quality and to produce virus-free plants, a study of an alternative vegetative propagation system was investigated. Corms of two cultivars: "Panorama" and "Rose Emperor" were surface-sterilised and the meristems of the sprouting buds were excised and multiplied in semisolid medium in the presence of BA at 2.22 μmol. For liquid culture initiation, the explants were transferred to glass jars containing the liquid media supplemented with BA (at 0, 2.22 or 4.44 μmol) in the presence or in absence of ANC (3.90 μmol). At the end of the second subculture, in the presence of BA at either 2.22 or 4.44 μmol, the biomass was at least doubled and significantly increased when compared to the control treatment. The addition of ANC appeared to inhibit biomass proliferation although in the medium containing 2.22 μmol BA + ANC, a high number of bulblets was counted per biomass (callus) unit. At the end of the second subculture (60 days) all the material was transferred to hormone-free medium and, after 30 additional days, the culture parameters were evaluated. In the cultures of both genotypes, several shoot primordia and complete small plantlets developed from the callus and the cell aggregates. The histological analysis of the calli and the behaviour of the neoformed propagules indicated the activation of the embryogenetic pathway in the presence of ANC. The plantlets were successfully acclimatised in the greenhouse.