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thidiazuron (TDZ) was studied to induce direct somatic embryogencsis and regeneration
from seedl~ng explants of Arochis l~ypogaeii (Gill and Saxena, 1992). Direct somatic
embryogenesls from zygot~c embryos derived from 40-day-old immature pods of Arachi~
i~ypoguea using 2,4-D were studied where various factors like growth regulators, sucrose,
genotypes and length of elnbryo~iic axis influenced frequency (Reddy and Reddy, 1993).
2,4-D-induced somatic elilbryoge~iesis was obtained from embryogenic calluses derived
from hypocotyls explants of Arucilis iiypoguea. High concentration of 2,4-D decreased the
frequency of somatic embryogencsis (Venkataclialam et al., 1997). Synthetic seeds oS
Arucl~is iijpogueu were obtained by encapsulatilig 5 to 30-day-old somitlc embryos and
geminated by on medium with various concentrations of sucrose, maltose, BAP and NAA.
25% of these embryos were filially converted into plantlets (Padmaja et al., 1995). A
refinement of embryo rescue technique to improve plant recovery from early heart shaped
embryos of interspecific hybrids of Pi~ascolur poiyutlrtlus and P. viilgaris was reported
(Geerts et al., 1999). Rates of ethyle~ic production were determined in highly embryogenic
and virtually non-embryogenic tissue cultures of Aledicago sarivu ssp. faicata during a 10-
day induction period on medium containing 2,4-D and kinetin, and during the first 10 d of
somatic embryo ibrmation on growth regulator-frcc medium. It was concluded from thesc
experiments that the high rates of ethylene product~on during embryo iilduction are not
essential for subsequent enibryo differentiation (Meijer, 1989). Efiicient plant regeneration
via somatic enibryogenesis has been developed in pigeonpea (Cajanvs cajan). Cotyledon
and leaf explants from 10-day-old seedlings produced embryogenic callus and somatic
embryos when cultured on MS supplenlented with 10 pM thidiazuron (TDZ). Subsequent
withdrawal of TDZ from the induction medium resulted in the maturation and growth of