PHOTOSYNTHETIC PHOTON FLUX DENSITY AND PLANT GROWTH REGULATORS AFFECT SOMATIC EMBRYOGENESIS IN AGAPANTHUS PRAECOX WILLD. SUBSP. ORIENTALIS (F. M. LEIGHT.) F. M. LEIGHT.

Callus was induced by using pedicel of Agapanthus praecox Willd. subsp. orientalis (F. M. Leight.) F. M. Leight. as explant, and then the effects of photosynthetic photon flux density (PPFD), auxin, paclobutrazol (PAC), and cytokinin (CTK) on the regeneration process of somatic embryogenesis were studied. The results showed that the requirement of proper PPFD in somatic embryogenesis was continuously enhanced. The reasonable PPFD for embryonic callus (EC) induction, somatic embryo (SE) induction, SE development, plantlet induction, and plantlet development were 0, 20, 20, 40, and 80 mu mol m(-2) s(-1), respectively. The gibberellin (GA) biosynthesis inhibitor PAC showed no significant effect on EC induction, and the browning rate was higher under a PPFD of 20 mu mol m(-2) s(-1) than in dark. The combination of 0.05 mg l(-1) N-(1-naphthyl) phthalamic acid (NPA) and 0.05 mg l(-1) PAC promoted SE induction. However, PAC showed an inhibitory effect on the development and maturation of SEs. The addition of 1.0 mg l(-1) 6-benzylaminopurine (BAP) and 0.1 mg l(-1) alpha-naphthaleneacetic acid (NAA) to the medium promoted plantlet induction and development, respectively. This study optimized the application of PPFD and PGRs in the somatic embryogenesis of A. praecox, which can promote the regeneration efficiency of this species in vitro via somatic embryogenesis.