Study of culture conditions for improved micropropagation of hybrid rose

An efficient protocol was developed for micropropagation of hybrid roses by manipulating growth regulators, photoperiods, gelling agent and subculture period. Multiple shoots were achieved from nodal explants of Rosa hybrida cvs. Cri Cri, Pariser Charme and First Red on the Murashige and Skoog (MS) medium supplemented with 1.5-2.0 mg/l BA (6- benzylaminopurine), 50 mg/l Ads (adenine sulfate) with 3% (w/v) sucrose. Inclusion of indole-3-acetic acid (IAA; 0.1-0.25 mg/l) into the cytokinin-rich medium promoted high frequency of shoot multiplication. The induction of multiple shoots was also affected by photoperiod and subculture period. Higher multiplication was achieved under 16 h photoperiod in all tested cultivars. The rate of multiplication was low when photoperiod both increased or decreased. The frequency of shoot multiplication was best up to the 6th to 7th subculture and thereafter it declined. Rooting was readily achieved upon transferring the microshoots onto half-strength MS medium supplemented with 0.25 mg/l IBA (indole-3-butyric acid) and 2% (w/v) sucrose. The percentage of rooting was less on MS medium containing NAA (1-naphthalene acetic acid) or IAA as compared with IBA. More than 60% of rooted plantlets were established in the greenhouse. The in vitro raised plantlets were grown normally and flowered within one month after their transfer to open field.