The effect of growth regulators in vitro phase on the quality of in vitro plantlets and microtubers in different cultivars of potato in a seed tuber production scheme

Experiments were conducted to determine the effects and post-effects of gibberellic acid (GA3) and chlormequat chloride (CCC) applying in vitro plantlet production (effects) and subsequent in vitro tuber production (after-effects) or on immediate in vitro tuber production (effects). Three concentrations of GA3 (0.1, 0.5 or 1 mg/l) and three doses of CCC (100, 500 or 1000 mg/l) with control were tested with the three cultivars (CV) namely Gloria, Marfona and Agria. To test direct effects on in vitro plantlet production plantlets were grown from explants on a standard medium containing Murashige and Skoog salts with normal vitamins. To test direct or post-effects on in vitro microtuber production the standard medium was used including 8% sucrose. The explants was treated with higher doses of CCC produced fewer stem branches on in vitro plantlets. The shortest plants with lowest numbers of leaves were observed in plantlets grown on media with 1000 mg/l CCC. Leaf area was the lowest with the highest doses of either CCC or gibberellic acid. Gibberellic acid increased the number of roots. Plantlets grown on the media with 1000 mg/l CCC produced shorter root systems. The direct effects of growth regulators on the number and size of microtubers were highly significant; both parameters were reduced by gibberellic acid. No direct effect of growth regulators could be observed for the weight of the microtubers. Post-effects of growth regulators on the number, size and weight of microtubers were also significant; cuttings from plantlets were pre-treated with CCC produced lowest numbers of microtubers with smallest size and lowest weight. Number, size and weight of microtubers were similar for the three cultivars.