In vitro Propagation of Ornamental Snapdragon (Antirrhinum majus L.) Revisited: An Analysis on the Effects of Plant Growth Regulators

Abstract

The effects of N6-(2-isopentenyl) adenosine (IP) and p-chlorophenoxyacetic acid (CPA) on the propagation of Antirrhinum majus have yet to be elucidated. This study compares plant growth regulators’ effects on enhancing propagation efficiency in snapdragon. In the seedling development phase, IP at 1.0 mg L-1 provided the highest germination ratio (91.11 ± 9.30%). The 6-benzylaminopurine (BAP) treatment at 1.0 mg L-1 gave the highest number of shoots (4.42 ± 0.30) whereas the medium with 0.50 mg L-1 IP triggered shoot elongation (3.80 ± 0.28 cm) from germinating seeds. The medium with 1.0 mg L-1 IP gave the highest number of leaves (12.33 ± 1.77) and roots (2.96 ± 0.32). IP treatment at 0.50 mg L-1 produced the greatest increase in seedling root lengths (2.50 ± 0.31 cm). In the shoot multiplication phase, thidiazuron (TDZ) at 1.0 mg L-1 gave the maximum number of shoots (10.04 ± 2.42 per nodal explant) while BAP treatment at the same concentration triggered shoot elongation (5.99 ± 0.29 cm). In the rooting phase, 3-indoleacetic acid (IAA) treatment at 0.50 mg L-1 induced the highest rooting rate (100%), root production (4.93 ± 0.48 per shoot), and root length (7.16 ± 0.97 cm). IAA treatments did not trigger callus production. However, the CPA treatments induced consistently higher callogenesis responses (96% and 100%), resulting in a minimal rooting response. The findings suggested using IP to increase seedling development without causing a restriction in root development, TDZ to improve shoot multiplication efficiency, and CPA to produce high-frequency calli production in ornamental snapdragon.