Protocol optimization for in vitro mass propagation of two sugarcane (<i>Saccharum officinarum</i> L.) clones grown in Ethiopia

Abstract

The present study was initiated to optimize in vitro protocol for mass propagation of two commercial sugarcane clones (Co 449 and Co 678) grown in Ethiopia through shoot tip culture. Experiments on shoot multiplication and rooting were laid out in a completely randomized design with factorial treatment arrangements. Shoot tips were surface sterilized with 5% active chlorinated Berekina for 25 min and initiated on Murashige and Skoog (MS) medium supplemented with 2 mg L^-1 6- benzylamino purine + 0.5 mg L^-1 indole-3- butyric acid. For in vitro multiplication, aseptically initiated shoot tips were treated with different concentrations and combinations of BAP and Kin using either sucrose or table sugar in separate experiments. For root induction, regenerated shoots were transferred onto half MS medium supplied with 6% sucrose or table sugar and different concentrations and combinations of IBA and NAA. With regard to shoot multiplication, genotype Co449 showed maximum regeneration frequency of 80% with 7.87 ± 1.06 shoots per explants on MS medium with 3% sucrose and 2 mg L^-1 BAP + 0.25 mg L^-1 Kin. On the same carbon source, genotype Co678 showed the highest multiplication frequency of 90% with 9.10 ± 0.10 shoots per explant on medium supplied with 2 mg L^-1 BAP + 0.5 mg L^-1 Kin. On MS with 4% table sugar and 2 mg L^-1 BAP + 0.25 mg L^-1 Kin, 80% of the transferred explants of genotype Co449 produced multiple shoots with an average number of 7.61 ± 0.10 shoots per explant while genotype Co678 showed the highest regeneration frequency (86.67%) with mean shoots number per explant of 8.36 ± 0.04 on medium supplemented with 2 mg L^-1 BAP + 0.5 mg L^-1 Kin. Half MS + 6% sucrose + 2.5 mg L^-1 IBA induced the highest rooting (86.67%) with an average root number per shoot of 16.53 ± 0.02 in Co449 cultures. In genotype Co678, ½ MS + 6% sucrose + 5 mg L^-1 NAA induced the highest rooting response of 80% with an average root number per shoot of 13.17 ± 0.29. Equivalent rooting responses were recorded on half MS medium supplemented with 6% table sugar. On½ MS with 6 % table sugar, 2.5 mg L^-1 IBA induced the highest rooting response (86.67%) and root number (15.93 ± 0.81) in genotype Co449 while 5 mg L^-1 NAA gave the maximum (80%) rooting with average roots per shoot of 13.93 ± 0.81 in genotype Co678. Rooted shoots were transplanted in the green house for hardening and different survival rate was recorded.

Keywords: Saccharum officinarum, multiplication, rooting, sucrose, table sugar, in vitro

African Journal of Biotechnology, Vol 13(12), 1358-1368