The effect of the culture media consistency on the organogenesis of potato meristem tips was evaluated on the in vitro isolation and multiplication stages from cultivars Baronesa, Eliza and Perola. The meristems were inoculated in liquid and semi-solid consistency isolation culture media. Meristems were cultivated in test tubes (20 x 150 mm) containing 5 ml semi-solid (6g L-1 agar) and liquid culture media (MS salts, 30g L-1 sucrose, 1.0 mg L-1 BA, 0.01mg L-1 NAA, 0.1 mg L-1 GA3). To the semi-solid media we added 300 mg L-1 of activated charcoal. As support for the meristems in liquid medium inverted "U" ribbon papers were used. After 30 days in the isolation medium, the differentiated meristems were transferred to liquid and semi-solid multiplication medium (MS salts, thiamine 1.0 mg L-1, panthotenic acid 5.0 mg L-1, GA3 0.25 mg L-1 and sucrose 20 g L-1) where they remained for a further 21 days. Meristem inoculation in the liquid multiplication medium presented at least four times higher shoots than those formed in semi-solid medium. The multiplication rate obtained in liquid culture medium was 1.6 and 3.6 times higher than in semi-solid medium when the meristems were differentiated in liquid and semi-solid media, respectively. Undesirable callus formation was observed on the basis of meristems developed in liquid medium, providing larger number of regenerated shoots from these meristems. The differentiation of potato meristems in semi-solid culture medium for 30 days followed by the cultivation in liquid media under agitation for 21 days, improved the growth and multiplication rates of potato meristems.
Solanum tuberosum; micropropagation; liquid medium
