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Bulb organogenesis of Tulipa tarda in vitro cultures in relation to light environment

ABSTRACT Here organogenesis of tarda tulip (Tulipa tarda Stapf.) from callus explants is presented. The callus tissue was cultivated on MS media containing 3% or 6% sucrose and either no addition of BAP (6-benzyl-aminopurine) or supplemented with 0.5 μM BAP. The cultures were maintained under a 16 h photoperiod under white, red or blue fluorescent light, at 20 ± 2°C for 12 weeks. This study aimed to determine the most suitable light conditions and medium composition for seed-derived callus explants in order to obtain an efficient formation of adventitious bulbs. There were no differences between the spectra of light in differentiating adventitious bulbs. Explants cultured in darkness (control), on 0.5 µM BAP and 3% sucrose, formed the highest number of adventitious bulbs. The efficiency of adventitious organogenesis amounted to 36.6 bulbs per 1 g of callus tissue. The fresh weight of biomass, cultured in these conditions, increased within 12 weeks from 1 to 6.99 g. Supplementation with BAP of the medium containing 3% sucrose promoted the formation of bulbs, but in the case of the medium with 6% sucrose, BAP had an adverse influence under every type of light. The obtained results provide a useful protocol for the micropropagation of T. tarda, which can be used commercially for rapid and cost-effective production of the tulip.