Acclimatization and flower induction of tissue culture derived cocoyam (Xanthosoma sagittifolium Schott) plants

Abstract

Expiants (shoot tips) were obtained for production of tissue culture plants, from cocoyam (Xanthosoma sagittifolium) plants growing in agroecological zone II (Cameroon) at the Root and Tubers Research Project (ROTREP) Biotechnology Laboratory at the Ekona Research Center. In order to utilize these tissue-culture derived plants (TCP) for field work, procedures for their acclimatization were developed. Three hundred plantlets were randomly selected from the first batch of 500 plantlets produced by ROTREP and acclimatized using 4 different growth media: i), sterilized vermiculite and sterilized top soil (SVMS, 50:50); ii), unsterilized vermiculite and unsterilized top soil (NSVMS, 50:50); iii), sterilized top soil (SS, 100%); and iv), unsterilized top soil (NSS, 100%). From the successfully acclimatized plants, 200 plants were taken for artificial flower induction studies. Gibberellic acid (GA3) was sprayed on the tissue culturederived cocoyam plants (TCP) at different concentrations (0, 500, 750, 1 000, 1 500 parts per million) for flower induction. There were no significant differences in growth of plantlets raised in the NSS medium and in the other growth media. Mean petiole length was in fact highest for plants acclimatized in NSS. Thus soil sterilization may not be critical for acclimatization of cocoyam plantlets. This is an important factor in the humid tropics, where resources are limited. Initial growth of plants was best for (GA3) sprayed compared to unsprayed plants. The highest number of inflorescences as well as pollen quantity was obtained at 750 and 1 000 ppm. Growth was significantly correlated with days to bracts and spadix formation. Flowering of tissue culture derived plants occurred 20-30 days earlier than that reported for non-tissue culture derived plants. © 1992.