Abstract:
The objective of the study was to evaluate the potency of Thidiazuron (TDZ) as a
plant growth regulator when compared to combined auxin (NAA) and cytokinin
(BAP) in evoking morphogenic responses from Alstroemeria aurantiaca cv. ‘Rosita’
shoot tip explants. Shoot tips cultured on basal medium devoid of any plant growth
regulators (PGRs) only increased slightly in length and formed only 1 leaf per shoot
during the culture period. The addition of various PGRs to the induction or culture
medium significantly influenced the number and length of shoots as well as the
number of leaves formed. While low concentrations of TDZ (0.1 μM) had no
significant effect and high concentrations (5.0 μM) were inhibitory, medium
concentrations (0.4‐1.0 μM) significantly increased the number and length of shoots
as well as the number of leaves formed from the explants. The longest shoots were
formed from explants cultured in media supplemented with 1.0 μM TDZ. Slightly
better but comparable responses were observed from explants cultured on media
supplemented with 1.0 mg/L BAP and low concentrations (0.01 mg/L) of NAA. The
explants cultured in 1.0 mg/L BAP + 0.01 mg/L NAA formed the greatest number of
shoots while those cultured in 1.0 μM TDZ formed the greatest number of leaves/
ex‐plant. Increasing the NAA concentration to 0.1 mg/L and combining this with
either 1.0 mg/L BAP or 1.0 μM TDZ depressed shoot formation and shoot length. In
conclusion, TDZ at concentrations between 0.4 and 1.0 μM were just as effective as
combined auxins (NAA) and cytokinin (BAP) in evoking morphogenic responses from
Alstroemeria aurantiaca cv. ‘Rosita’ shoot tip explants.
