Fig. 2

Representative protocorms of Vanilla planifolia after different treatments of seeds. Cultures were incubated for 5 months on BM1 medium at 30 °C in dark. Mature seeds were disinfected with solutions of HCl (A–D), solutions of H₂SO₄ (E—Immature seeds excerpted from surface sterilized unripe pods served as a positive control as they lack dormancy (J). The seed treatments were (in the same order as in Fig. 1A): 30 min 0.1 M HCl (A), 30 min 0.1 M HCl + pepsin 0.5 g/100 ml (B), 4 h 0.1 M HCl + pepsin 0.5 g/100 ml (C), 15 min 35–38% HCl (D), 3 min 50% H₂SO₄ (E), washed in 50% H₂SO₄ (F), 5 min 50% H₂SO₄ (G), 5 min 96% H₂SO₄ (H), 30 min Chlorinated lime 66 g/l (I). Scale bars 1 cm