DEVELOPMENT OF HAPLOID ASPARAGUS EMBRYOS FROM LIQUID CULTURES OF ANTHER-DERIVED CALLI IS ENHANCED BY ANCYMIDOL

The effect of ancymidol concentration on the development of haploid asparagus embryos was determined. Liquid cultures from anther-derived calli were grown for three weeks in MS medium plus 1.0 mg l-1 2,4-D, 0.1 mg l-1 NAA, 0.2 mg l-1 kinetin, 800 mg l-1 glutamine, 500 mg l-1 casein hydrolysate, 2% sucrose and 0.0-1.0 mg l-1 ancymidol. Cell clumps (224-500 mum) were plated on solid embryo maturation medium (MS medium plus 3% sucrose, 0.1 mg l-1 NAA, 0. 5 mg l-1 kinetin and 0.0-1.0 mg l-1 ancymidol) and grown for eight weeks. Ancymidol enhanced embryo maturation and germination and was more critical in the solid than liquid medium. Total embryo number did not vary among most treatments. The best response was observed when ancymidol concentrations were 0.1 and 0.5 mg l-1 in the liquid and solid media, respectively; two-thirds of the embryos produced were bipolar and 35 % of bipolar embryos germinated. Seven to 82% of plants recovered from different ancymidol treatments were haploid; the others were diploid, triploid or chimeric for ploidy level.