Pawełczak A., Majewska A., Geszprych A., Dąbrowska B.

Virus-free plant material obtained by meristem cultures of seven cultivated Polish types of horseradish (Armoracia rusticana Gaertn.) was used as a source of leaf and root explants. The effect of explant type, composition of medium, and root storage at 5oC on shoot regeneration was evaluated. Shoot regeneration from leaf explants on MS medium supplemented with 0.5 mg L-1 naphtaleneacetic acid (NAA) and 0.1 mg L-1 benzyladenine (BA) was more effective than on LS medium with 0.8 mg L-1 indole-3-acetic acid (IAA) and 4 mg L-1 kinetin. No significant differences in shoot regeneration from the top, middle and basal part of leaf blade were observed. Root explants afforded possibilities for better shoot regeneration than leaf explants. Concentration of BA (0, 0.05, 0.1, 0.2, and 0.4 mg L-1) in MS medium did not affect the number of shoots regenerated from root explants, but it affected shoot weight. The optimal BA concentration appeared to be 0.1 mg L-1. Higher BA concentration resulted in leaf deformations and inhibition of rooting. The shoots regenerated on MS medium were characterised by higher weight than those obtained on 1 MS (containing half of the original concentration of macronutrients). Storage of isolated roots at 5oC for 4 weeks stimulated their capacity for shoot regeneration. The results of the experiments indicate that the conditions of in vitro horseradish regeneration (the composition of medium and the storage period of isolated roots) should be adapted to the particular horseradish type.

Key words: root and leaf explants, shoot regeneration, benzyladenine, macronutrient concentration, storage