Micropropagation of cocoyam (Xanthosoma sagittifolium L. Schott) in temporary immersion bioreactor

This study aims at establishing a temporary immersion technique for large-scale propagation of cocoyam (Xanthosoma sagittifolium). Sucrose was experimented with as a determinant factor for shoot multiplication in this culture system. The highest proliferation rate (68 ± 7) occurred with 20 g l⁻¹ sucrose in the culture medium. This concentration appeared to be the optimal amount due to its promoting effect on plantlet development. The acclimatized plantlets showed a continuous effect of sucrose treatment during ex vitro growth, especially in low sucrose concentration. This fact is evidenced by the low survival rate (0.13 ± 0.12) and the poor chlorophyll content (1.180 ± 0.076 mg g⁻¹) recorded on plantlets derived from 15 g l⁻¹ of sucrose. The treatment with 60 g l⁻¹ of sucrose prior to acclimatization was efficient for roots induction and elongation. The analysis of pH revealed a fluctuation from one subculture to another, with an overall pH decrease under all treatments tested and, thus, indicates that plants release proton during growth. This feature had an impact on in vitro plantlets growth. The potentiality of the temporary immersion technique to foster the production of Xanthosoma sagittifolium is discussed.