提高木薯循环培养的次生体胚再生植株频率研究

用木薯成熟体胚子叶作外植体诱导次生体胚，接种7d或15d后分别在诱导培养基或成熟培养基中加入AgNO3，可明显提高植株再生频率。前者可使体胚再生植株频率由对照的40．5％提高到58．1％；后者可使植株再生频率由对照的36．1％提高到61．3％。用ABA进行上述处理，效果更加显著。诱导期处理，可使植株再生频率由对照的40．5％提高到72．6％；成熟期处理，植株再生频率由对照的36．1％提高到81．3％。若诱导7d后，将2，4－D浓度由4．0mgL-1降至2．0mgL-1，并加AgNO3，继续诱导15d，转到附加0．25mgL-1ABA的成熟培养基中培养至30d，能极显著地促进体胚的发育和成熟，使植株再生频率达到一个相当高的水平，最高达95％，平均每个外植体产生的植株数达39．6个，分别相当于对照的2．38倍和2．46倍。

IMPROVEMENT OF PLANT REGENERATION FROM CYCLIC SECONDARY SOMATIC EMBRYOS IN CASSAVA (MANIHOT ESCULENTA CRANTZ)

Cotyledons from mature embryos of cassava cultivar Nanzhi 188 selected from cultivar CM321 - 188, which was provided by CIAT (Centro internacional de Agricultura Tropical), were used as explants. AgNO3 could obviously promote the plant regeneration frequency (PRF) in the induction medium (MS I) with 16 mg L-I AgNO3 added at the 7th day, and in maturation medium (MS II) with 20 mg L-l AgNO, added at the 15th day, the PRF being from 40.5% (control) to 58.1 %, and from 36.1 % (control) to 61.3%,respectively. 0.25 mg L-1 ABA adding to MS I and to MS II could markedly improve PRF by 32.1 % and 45.2%, respectively. An decreasing concentration of 2,4-D at 2.0 mg L-1 plus 16 mg L-1 AgNO3 and 0.25 mg L-1 ABA in combination signifcanlly improved somatic embryo maturation and promoted to form normal shoots, the highest PRF was 95%, and the number of plantlets produced reached 39.6 per explant.