The developed embryos (1.5 cm in diameter) were inoculated onto MS agar media containing low concentra- tion of 2,4-D (0.2–0.5 mg l1) and other phytohormones (Kn, BA and NAA) and incubated under an illumination of 45–55mmol m2 s1 for 15 h per day at 26 1 8C.