TEMPERATURE AND GENOTYPE AFFECT ASPARAGUS SOMATIC EMBRYOGENESIS

Calluses from five asparagus genotypes, G14, G32, G171, G203, and G447 and hybrid Jersey Giant (JG) were incubated at three-temperature regi mes (24, 27, and 30 degrees C) on embryo induction medium to assess so matic embryo development and conversion to plantlets. The calluses fro m three genotypes (G14, G32, and G171) were not responsive, failing to produce somatic embryos at any temperature regime. For three responsi ve genotypes (G203, G447, and JG), both incubation temperature and gen otype significantly affected the numbers of somatic embryos produced. The calluses produced the most and the least numbers of total, bipolar , and globular embryos when incubated at 27 degrees C and 24 degrees C , respectively. When incubated at 27 degrees C, G203 produced the high est numbers of total and globular embryos, 178 g(-1) callus and 142 g( -1) callus, respectively, while G447 produced the highest number of bi polar embryos, 77 g(-1) callus. Incubation temperature but not genotyp e significantly affected the conversion of somatic embryos to plantlet s. The somatic embryos recovered from the three responsive genotypes i ncubated at 27 degrees C also converted to plantlets at the highest fr equencies, 60-63% of the bipolar embryos and 42-43% of the globular em bryos converted to plantlets, while the somatic embryos recovered from the calluses incubated at 24 degrees C converted to plantlets at the lowest frequencies.