ANDROGENIC ABILITY AND CHROMOSOME DOUBLING BY DIFFERENT COLCHICINE TREATMENTS IN ANTHER CULTURE OF HEXAPLOID WHEAT GENOTYPES (TRITICUM-AESTIVUM L.)

Five spring hexaploid wheat genotypes were evaluated for their androge nic ability, rate of spontaneous chromosome doubling and efficiency of different colchicine treatments on plantlets, and on embryoids obtain ed 45 days after anther culture. A concentration of 500 mg/l of colchi cine was used for 1 or 3 days for embryoid treatment. Results show sig nificant genetic effects on androgenesis parameters; 'Yecora Rojo' and 'Pavon' being the best genotypes. Total, green and albino regeneratio n rates decreased when embryoids were colchicine treated. In most case s there were no significant differences between 1 or 3 days treatment, except for PI-49 and 'Chenab' genotypes which could not regenerate gr een plants with 3 days treatment. Chromosome doubling rates varied acc ording to genotype. Spontaneous doubling ranged from 0% for PI-49 and 'Chenab' genotypes to 56% for 'Yecora Rojo'. Chromosome doubling rate was at least 50% and raised to 100% in some cases when embryoids were colchicine treated, but because of a low regeneration frequency of the se embryoids, treatment efficiency remained low. We propose that embry oid treatment with colchicine be recommended, for genotypes producing a high number of embryos or those which have a low rate of spontaneous chromosome doubling.