In vitro shoot regeneration of gladiolus in semi-solid agar versus liquid cultures with support systems

Multiple shoot clusters of gladiolus were established in semi-solid agar (AS) and liquid media appended with membrane raft (MR) and Duroplast foam (DF) support matrix. A difference in optimum combination of α-napthaleneacetic acid (NAA)/6-benzylaminopurine (BAP) for shoot multiplication was noted with culture systems. Maximum regeneration of 33.15 shoots/cluster was obtained with 1 mg l^-1 NAA and 2 mg l^-1 BAP in liquid medium with membrane support. There were 33.46 and 25.37% increase in shoot regeneration in MR system than AS and DF systems, respectively. Shoot multiplication was rapid in AS and MR systems (relative differentiation rate of 5.7% per 7 days of incubation) when compared to DF system (relative differentiation rate of 4.6% per 7 days of incubation). Shoot multiplication followed a linear trend with incubation time, whereas shoot elongation fitted well with quadratic functions. Such analysis suggests that shoot number increases steadily with time, whereas the rate of shoot elongation was different at different phases of incubation in different culture systems. Shoots in DF system exhibited faster elongation than those in AS and MR systems.