| Abstrakt: |
Explants (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 culture-derived 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. Acclimatation et induction florale chez le malanga (Xanthosoma sagittifolium) produit ? partir de culture de tissu. Afin d'utiliser des plants obtenus par culture de tissus (TCP) pour un travail en champ, nous avons d?velopp? des proc?dures d'acclimatation de ces plants. Les explants de malanga (Xanthosoma sagittifolium), destin?s ? la production de plants par culture de tissus au laboratoire de biotechnologie du Centre de recherche d'Ekona (projet de recherche sur les racines et tubercules ROTREP), provenaient du Cameroun, zone agro?cologique II. Trois cents plantules, parmi le premier lot de 500 produit par ROTREP, furent choisies au hasard et acclimat?es en utilisant 4 diff?rents milieux de culture: - vermiculite st?rilis?e et sol superficiel st?rilis? (SVMS 50:50); - vermiculite et sol superficiel non st?riles (NSVMS 50:50); - sol superficiel st?rilis? (SS 100%); - sol superficiel non st?rile (NSS 100%). Deux cents plantes furent pr?lev?es parmi les plantes acclimat?es pour l'?tude de l'induction florale. De l'acide gibb?rellique (GA3) ? diff?rentes concentrations (0, 500, 750, 1 000, 1 500 ppm) fut pulv?ris? sur les plantules. Aucune diff?rence de croissance significative ne fut observ?e entre les plantules obtenues dans les diff?rents milieux de culture. La longueur moyenne du p?tiole ?tait cependant plus importante pour les plantules cultiv?es sur NSS. Nous en d?duisons que la st?rilisation du sol n'est pas un ?l?ment critique pour l'acclimatation de plantules de malanga. Ceci est important dans les zones tropicales humides o? les ressources sont limit?es. La croissance initiale des plantules fut meilleure pour les plantes trait?es au GA3que pour les plantes non trait?es. Les meilleurs r?sultats en nombre d'inflorescences et en quantit? de pollen furent obtenus pour des doses de 750 et 1 000 ppm. La croissance fut significativement corr?l?e ? la date d'apparition des bract?es et du spadice. La floraison de plantes issues de culture de tissus eut lieu 20-30 j plus t?t que celle de plantes normales. |
