Effect of PGRs and Nature of Ex-plant on Plant Regeneration in Red Sorghum Karandafi (Sorghum bicolor (L.) Moench) through Somatic Embryogenesis

Sorghum bicolor is an important cereal crop grown in the tropics, subtropic and temperate regions as
well as in poor quality soils and semi-arid regions. To obtain immature embryo throughout the year is
not easy because sorghum flowering occurs once in its life time. In this study, an optimum protocol for
shoot formation through somatic embryogenesis using mature embryo explants was developed. Calli
were initiated on Murashige and Skoog (MS) media supplemented with varying concentration of 2,4-
Dichlorophenoxyl acetic acid (2,4-D) ranging from 1.5 mg/l -4.0 mg/l alone or in combination with 0.5
mg/l Kinetin (KN). Significance difference (p < 0.05) was observed among the different concentrations
of hormone used for callus induction. The highest percentage callus formation was obtained from the
media fortified with 4 mg/l 2, 4-D for mature embryo obtained from imbibed seed while for the
preconditioned mature embryo, the media supplemented with 2 m/l 2,4-D + 0.5 mg/l kinetin (KN)
recorded more percentage callus formation compared to what was obtained from the media
supplemented with 2.5 mg/l2,4-D + 0.5 mg/l. More percentage shoot formation was obtained from the
media supplemented with 1 mg/l 6-benzylaminopurine (BA). Average number of shoot per callus was
also more in the media fortified with 1 mg/l BA (2.25) but this was not significantly different from what
was obtained from the media fortified with 2 mg/l BA+ 0.1 mg/l 2,4-D at 5% level of significance. It
was observed that better response was obtained when the mature seeds were preconditioned on
hormone free media before it was taken to callus induction media. In conclusion, a protocol for shoot
formation had been optimized using mature embryo. This showed that there was a possibility of
improving regeneration from mature embryo by preconditioning the mature seed on hormone free
media before inoculation.