Comparative study of morphological parameters of Grand Nain banana (Musa AAA) after in vitro multiplication with growth retardants

The incorporation of growth retardants (GR) such as ancymidol (ANC) or paclobutrazol (PBZ) in liquid culture media during multiplication stage of bananas decreases the excessive growth of stems and leaves. However, it is unknown if these chemicals have residual effect on further plant growth. To study the effect of ANC and PBZ on Grand Nain banana shoots, they were subcultured for five cycles in the multiplication stage and evaluated in elongation-rooting and acclimatization stages. Multiplication basal medium was Murashige and Skoog supplemented with 1.0 mg l−1 thiamine-HCl and 17.7 μM 6-benzylaminpurine (6-BAP), 9.75 μM ANC or 8.5 μM PBZ. Multiplied Grand Nain banana shoots were transferred to elongation-rooting stage and later on to ex-vitro conditions. The evaluation of GR residual effect and somaclonal variation on Grand Nain banana plants was determined through a comparative study of several morphological parameters in elongation-rooting and acclimatization stages. All morphological parameters evaluated in the elongation-rooting stage showed a similar performance with the exception of the pseudo-stem diameter of the vitroplants treated with both GR. There were significant differences for plant height in the acclimatization stage when shoots were multiplied in a medium containing ANC. The similarities of the parameters evaluated in both stages and the normal morphology recovery of vitroplants multiplied with PBZ suggest that there were no residual effects by adding PBZ to the culture media. The addition of ANC induced significant differences in plant height during the acclimatization stage.