Effect of cytokinin content of the regeneration media on in vitro rooting ability of adventitious apple shoots

Rooting ability of ‘Royal Gala’ shoots regenerated on media with different cytokinin content (thidiazurone, benzyladenine, benzyladenine-riboside and meta-topolin-riboside) was observed directly after regeneration and compared after subculture on hormone-free medium (A), or on medium with decreased cytokinin content (B), or elevated gibberellic acid (GA3) content (C) for a week, or after a subculture on proliferation media (1.0 mg l−1 benzyladenine-riboside) for four weeks (treatment D). Rooting and acclimatization of regenerants after directly regeneration was not successful. Subculture of shoots on hormone-free medium did not improve the rooting ability of shoots, while their subculture on B and C media resulted in up to 36% rooting rate depending on regeneration media from which the shoots originated. The best rooting rate (up to 76%) was achieved in shoots regenerated on medium with benzyladenine-riboside after treatment D similarly to rooting ability of micropropagated shoots (80%). The rooting capacity of shoots depended on both the cytokinin content of the regeneration media and different subculture media used. All rooted shoots survived after acclimatization.

► Rooting of shoots regenerated on media contained different cytokinins was studied. ► Rooting ability was affected both by regeneration and subculture media. ► Regeneration with TOPR decreased the rooting ability of shoots. ► Best rooting (76%) was achieved after regeneration with BAR.