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

Abstract:

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^-1 AgNO3 added at the 7th day, and in maturation medium (MS II) with 20 mg L^-1 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.