Improved culture conditions for somatic embryogenesis from Asparagus officinalis L. using an aseptic ventilative filter.

Calli were induced from the crown of seedlings or lateral bud of young spears of Asparagus officinalis L. on Linsmaier and Skoog's (LS) solid-medium supplemented with 5 μ M 2,4-dichlorophenoxyacetic acid (2,4-D). Embryogenic callus was selected from induced calli and proliferated in LS liquid medium supplemented with 5 μ M 2,4-D. Non-vitrified somatic embryos were formed and efficiently developed into club-shaped embryos in LS hormone-free medium with 1 % gelrite in a culture vessel capped with an aseptic ventilative filter. Non-vitrified club-shaped embryos developed into normal plants when transferred to half-strength LS medium without hormones, and 0.8 % agar. Carbon dioxide concentration and moisture content inside the culture vessels were measured, and their effect on embryo development is discussed.