Shoot tips with 2 leaf primordia were cultured to induce shoot primordia in MS liquid medium supplemented with several concentrations of BA and hIAA under the conditions of 10,000 lux illuminations for 24 h and of vertical shaking of 2 rpm in carrot. ...
Shoot tips with 2 leaf primordia were cultured to induce shoot primordia in MS liquid medium supplemented with several concentrations of BA and hIAA under the conditions of 10,000 lux illuminations for 24 h and of vertical shaking of 2 rpm in carrot. Two F$_1$ hybrids and two male sterility lines were used. Shoot primordia were only induced in the medium supplemented with 2.0 mg/L of BA and 0.2 mg/L of NAA. Genotypic specificity and seasonal effect of donor parents on shoot primordia induction were not observed and average 15-20% of the planted dornes developed to shoot primordia. The induced shoot primordia were successfully propagated by subculture in the same medium. However, they were grown into three different types during multiplication, that is, the type with multiple small shoots on the surface, the type of without any shoot, and the type of callus. Shoot primordia clusters with small shoots on the surface differentiated multiple shoots successfully in 1/2 MS solid medium supplemented with 0.2 to 1.0 mg/L of IAA and 0.2 to 1.0 mg/L of kinetin. New shoot primordia with small shoots were well formed when pieces bigger than 2 mm in diameter of the out layer of the shoot primordia cluster with small shoots were subcultured. No differences of multiplication and shooting ability and chromosomal variation of shoot primordia were observed until the 13th sub-culture.