Comparison of agar and an agitated, thin-film, liquid system for micropropagation of ornamental elephant ears

Micropropagation of black-stemmed elephant ear (C esculenta (L.) Schott 'Fontanesii')' and upright elephant ear (A. macrorrhizos G. Don) were compared in semi-solid agar media and agitated, liquid thin-film bioreactor vessels at four explant densities (33, 100, 165, and 330 explants/L of media) using two growth regulator combinations: 1) 1 muM benzylaminopurine (BA)-growth medium, and 2) 3 muM BA plus 3 pm aneymidol-multiplication medium. The thin-film liquid system outperformed agar culture for most measured responses. Some exceptions were relative dry weights at higher explant densities and multiplication rate of Colocasia. When the thin-film liquid system was compared to agar culture, Alocasia explants produced their greatest biomass and had the least residual sugar at the highest explant density. Alocasia explants multiplied most rapidly and had the greatest relative dry weight on liquid media at the low explant densities. Alocasia plants were larger in growth medium than multiplication medium and larger in liquid medium than agar medium. When compared to agar, Colocasia in the thin-film liquid system produced the greatest biomass at the highest explant density in growth medium, had the greatest relative dry weight at the lowest explant density, and used the most sugar at the highest explant density. Alocasia and Colocasia would likely produce greater fresh and dry weight at the highest explant density if additional sugar were supplied during thin-film culture. Greater growth in thin-film culture of Alocasia and Colocasia is due in part, to greater availability of sugar in liquid compared to agar medium.