Direct shoot organogenesis on hypocotyl explants from in vitro germinated seedlings of Psidium guajava L. cv. Allahabad Safeda

Multiple shoots were generated via direct organogenesis on hypocotyl segments excised from in vitro germinated seedlings (45-day-old) of Psidium guajava L. cv. Allahabad Safeda. Modified basal Murashige and Skoog (MMS) medium supplemented with 6-benzylaminopurine (BAP), zeatin or thidiazuron with or without α-naphthalene acetic acid (NAA) were tried. Thidiazuron (0.1 μM) along with 0.54 μM NAA gave the highest response (44.6%) with the regeneration of 3.6 shoots per original explants. These shoots upon subculture gave rise to about 5.0 shootlets per explant in shoot proliferation medium, i.e. MMS supplemented with 2.22 μM BAP + 2.32 μM kinetin. The regenerated microshoots were elongated using a quick dip of gibberellic acid (GA₃; 1.44 mM) prior to culture on MMS medium supplemented with 0.88 μM BAP and adenine sulphate (54.29 μM) for 2 weeks. Rooting of microshoots was achieved best on half strength MMS medium supplemented with 4.90 μM indole-3-butyric acid along with 100 mg l⁻¹ activated charcoal.