Des ignames (Dioscorea cayenensis ) et des bananes plantains (Musa paradisiaca ) ont subi divers traitements physico-chimiques pour prolonger la dormance des ignames et retarder le mûrissement des bananes plantains. Nous avons observé que les inhibiteurs de la germination habituellement utilisés sur la pomme de terre sont inefficaces sur les ignames. Quant à l'acide gibbérellique, il permet de prolonger sensiblement la dormance chez l'igname. La conservation par le froid entre 16°C et 20°C permet d'inhiber de façon notable la germination et fait éviter les pertes excessives de poids. En ce qui concerne la conservation en atmosphère contrôlée, on a pu conserver pendant deux mois des bananes plantains vertes à 20°C. Les rayonnements ionisants à la dose de 0,08 à 0,12 KGY inhibent la germination des ignames. ----- Yams (Dioscorea cayenensis ) and plantain bananas (Musa... ) were submitted to various post-harvest treatments and then kept for several months. The physico-chemical treatments were designed to prolong dormancy of yams and delay ripening of plantain bananas. We observed that inhibitors of germination, employed routinely in the case of potatoes, were ineffective for yams. Treatments with giberellic acid, however, led to a significant prolongation of dormancy in the case of the yam. Storage at low temperature, i.e. between 15 and 20°C, inhibited germination significantly and avoided excessive loss of weight. With respect to controlled gas storage, plantain bananas were kept at the green stage during two months at 20°C. Ionizing radiation at a dose of 0.08 - 0.12 KG Y inhibited the germination of yams.