Comparison of the effects of cytokinins and chitosan on in vitro seed germination and organ development in radish

Abstract

Comparative determination of the effects of plant growth regulators and chitosan on several plants suggested a cytokinin-like effect of chitosan in in vitro plant propagation. Therefore, we evaluated the impact of several cytokinins and chitosan on in vitro seed germination and organ development in Raphanus sativus ‘Cherry Belle’. The effects of 6-Benzylaminopurine (BAP), kinetin (KIN), zeatin (ZTN), thidiazuron (TDZ), N⁶-(2-Isopentenyl)adenosine (2IP), and chitosan (CHT) were tested on plants. All the treatments enhanced seed germination. Hypocotyl elongation remarkably increased after CHT treatments, whereas cytokinins reduced the parameter. Low concentration of KIN (0.25 mg L^− 1), high concentration of 2IP (2.0 mg L^− 1), and CHT treatments (2.5, 5.0, and 10.0 mg L^− 1) led to a limited increase in leaf production. All cytokinin treatments reduced root elongation, whereas CHT treatments (2.5, 5.0, and 10.0 mg L^− 1) induced statistically significant increases in the parameter. The highest concentration of 2IP elevated tuberization frequency, while all cytokinin treatments led to an early tuberization. However, CHT treatments did not induce tuberization, which was persistent even during an extended incubation period. The 2IP treatments at 0.5 and 1.0 mg L^− 1 stimulated the development of tubers with similar thermotropic properties to the roots produced in the presence of CHT in culture medium. The CHT treatments led to partially similar germination and organ development patterns only with low concentrations of KIN (0.25 and 0.50 mg L⁻¹). These findings suggest that CHT may have a variety of distinct roles than cytokinins tested on the organ development in radish, with significant effects on hypocotyl and root development. Therefore, future studies into the comparative impacts of CHT and auxins on radish cultivation would also be useful.

Key Message

Chitosan may play different roles than cytokinins on organ development in radish, with its considerable impacts on hypocotyl and root elongation.