Effect of growth regulators and gelling agents during regeneration. Regeneration frequency (%)* of four rice cultivars; IR64, PB1, CSR10 and Swarna using MSRMa (a) or MSRMb (b) medium containing varying concentrations of agarose. Data shown are mean ± standard deviation of three independent experiments. For each cultivar, the statistical significance of the effects of different concentrations of agarose and the media components (MSRMa or MSRMb) on regeneration frequency was tested using two-way ANOVA (P < 0.0001) followed by Tukey HSD test (HSD0.5). *Regeneration Frequency (%) = no. of microcalli regenerating shoots/no. of microcalli incubated × 100%. pAgarose concentration used throughout the regeneration i.e. in both the phases of regeneration. q1% agarose was used during the first phase of regeneration and 0.4% in the second phase. r1% agarose was used during the first phase of regeneration and 0.8% in the second phase.