INVITRO REGENERATION FROM IMMATURE EMBRYO CALLUS IN MAIZE - QUANTITATIVE ASPECTS AND TRANSMISSION THROUGH CROSSES

Immature embryos from several Zea mays lines were grown in vitro in order to study plant regeneration rate quantitatively according to two criteria: the proportion of morphogenous embryos and the yield of plants from them. The proportion of morphogenous embryos was strongly dependent on genotype; this property was cross-transmissible. Neither the duration of primary culture nor the growth regulators used (2,4-D or pCA) seemed to have a determining effect. However, a mother plant effect was observed. The number of regenerated plants also seemed linked to genotype; for all tested lines, embryos between 1 and 2.15 mm were more prolific. Plant yield rates were very variable. On regenerated plants transplanted in the greenhouse, a decrease in size and leaf number was observed. All cytologically checked individuals showed 20 chromosomes.