Effect of exogenous phytohormones and sucrose on micropropagation and microtuberisation of Manihot esculenta Crantz var. TMS 96/0023

Abstract

The effect of exogenous phytohormones and sucrose on micropropagation and microtuberization from nodal cuttings of Manihot esculenta was studied. Direct and indirect organogeneses were established from these explants. When nodal cuttings were cultured in the presence of 0.01 to 0.1 mg.L^-1 of BAP or NAA there was induction of the budding of axillary buds, with the highest percentages of nodal cuttings with axillaries buds budded of 98 and 73% with 0.07 mg.L^-1 BAP and 0.05 mg.L^-1 NAA, respectively. When sub cultured in the presence of 0.05 to 0.1 mg.L^-1 NAA, the nodal cuttings with axillaries buds budded produced yellowish and friable callus with the highest percentage of callogenesis of 59.8% with 0.08 mg.L^-1 NAA. The highest fresh weight of callus of 1334.7 mg was obtained with 0.07 mg.L^-1 of NAA. When sub cultured in the presence of 0.05 to 0.1 mg.L^-1 BAP, the nodal cuttings and callus induced shoots with the highest percentages of 72.3% and 92.3% for nodal cutting and callus respectively with 0.08 mg.L^-1. Also, the highest numbers of shoots per nodal cutting 17.9 and per callus 28.1 were obtained with 0.08 mg.L^-1. Multiple shoots, when isolated from nodal cuttings or callus and sub cultured in the presence of different ratio of BAP/NAA, differentiated into plantlets. With 0.07/0.05 mg.L^-1 and 0.08/0.05 mg l^-1 ratio, all shoots (100%) gave rise to plantlets with the highest growth parameters (14.8 ± 3.1 to 15.3 ± 1.7 cm of high, 12.3 to 12.7 leaves and 7.8 to 8.3 roots). These plantlets were used to induce microtubers on the basal medium supplemented with 0.1 to 0.6 mg.L^-1 of NAA or Kin or NAA/Kin ratio and 10 to 60 g.L^-1 sucrose. The ratio NAA/Kin of 0.4/0.4 mg.L^-1 combined with 20 to 30 g.L^-1 sucrose was more effective on the microtuberization than NAA and Kin used separately. In fact, it gave rise to 57.8 to 61.3% of plantlets which produce microtubers with the highest number of microtuber per plantlet (4 to 5), the highest diameter (130.4 to 131.8 mm) and the highest fresh weight of microtubers (403.3 to 408.1 mg). When the plantlets were acclimatized in different substrates, 100 % survived in the mixture red soil/black soil at equal volume (V/V) These results of this work show that BAP, NAA, and Kin used separately or in ratio can be used for organogenesis and micropropagation in Manihot esculenta var TMS 96/0023 in vitro.

Keyword: NAA, Kin, BAP, sucrose, organogenesis, microtuberization, cassava.

African Journal of Biotechnology, Vol 13(39) 3966-3976