INFLUENCE OF MERISTEM-TIP SIZE AND LOCATION ON MORPHOLOGICAL DEVELOPMENT IN DIOSCOREA-CAYENENSIS DIOSCOREA-ROTUNDATA COMPLEX GROSSE-CAILLE AND ONE GENOTYPE OF DIOSCOREA-PRAEHENSILIS

In vitro morphological development of meristem-tips, excised from micr oshoots, is reported for one clone 'Grosse Caille' of D. cayenensis-D. rotundata complex and for one clone of D. praehensilis. The effects o f size and location of meristem-tip on viability and morphological dev elopment after 3, 8 and 11 months in vitro culture were studied. The l arger size of meristem-tip gave the best rooting and plantlet formatio n while the smaller size gave the best bud production. Axillary buds w ere more reactive than apical meristem-tips in callusing and rooting w hen small-sized meristems of the 'Grosse Caille' clone were used; the use of larger meristem-tips did not induce more differences between ap ical and axillary buds. The production of plantlets was successful, af ter 11 months of culture, with a score of 82 and 39% survivors, for 'G rosse Caille' clone and D. praehensilis genotype, respectively.