GENOTYPE, TEMPERATURE, AND SAMPLING DATE AFFECT EMBRYOGENESIS IN ASPARAGUS ANTHER CULTURE

Asparagus (Asparagus officinalis L.) anthers from flowers of field-gro wn plants were cultured for five genotypes, four incubation temperatur es, and three sampling dates. Treatments were evaluated for total and embryogenic callus production. Incubating anthers at 35C was optimal f or initiating embryogenic callus for three genotypes. Another line per formed best and equally well at 29 and 32C, while one was recalcitrant to embryogenic callus formation at the temperatures evaluated. For al l genotypes, almost half of the anthers produced callus for at least o ne temperature treatment, but the percentage of these calli that was e mbryogenic ranged from 0% to 50%. Sampling date affected response only for specific genotype-temperature combinations. Embryo recovery range d from six to 14 per callus. For the four responsive genotypes, 77% to 100% of plantlets was haploid. Culturing anthers at several temperatu res ranging from 29 to 35C, with repeated samplings of flowers from th e field, likely will allow recovery of haploid embryos from many selec tions. This result will expand the germplasm base to develop all-male asparagus hybrids.