Influence of different substrates on in vitro initiation of some early and late cultivars of globe artichoke [Cynara cardunculus L. subsp scolymus (L.) Hayek]

The interest is rising for a qualified nursery activity of globe artichoke, which may ensure growers healthy plants of selected varieties. In vitro propagation by meristem represents the only way to restore health of propagation material maintaining the variety conformity but a further effort is still necessary to assess a suitable in vitro propagation technique for every variety. Genotypical differences in fact, play an important role in the response to in vitro culture and especially for early cultivars a standard method of propagation has not been established. In this paper, the results are referred of a trial aiming at evaluating the influence of six different substrates on the initiation phase of five varieties (Tema, Violet of Provence, Spinoso of Palermo, C3 and Exploter) traditionally or recently introduced in cultivation. The six media differed for mineral, additive and hormonal composition. Only two of the studied substrates differed only for the mineral composition since the Tendil and Lecerf (TL) salts substituted MS ones. Among the substrates so far tested, best results (on average 81% normal shoots) were obtained by thF1 medium containing macro- and microelements of TL, Gamborg vitamins, (25 mg L-1), meso-inositol (100 mg L-1), thiamine (HCL) (0.4 mg l(-1)), 2iP (1 mg L-1), IAA (1 mg L-1) and GA(3) (0.025 mg L-1). Moreover, in the initiation' phase, the mineral composition of the medium plays an important role since percentage of vitrified and browned apex noticeably increased when the TL macro and micro elements were substituted by the MS ones.