Abstract:

The first and second leaf from the top of Phalaenopsis amabilis seedlings were used respectively as explants，and 1/2 MS medium including 10% Coconut Milk (CM), 0.1 mg·L^-1　α-Naphthyl Acetic Acid (NAA), 1.0 mg·L^-1 Thidiazuron (TDZ) and 0.5% agar was used to induce PLB, the effects of wound and high osmotic pressure on PLB（protocorm-like body）induction were studied. The results revealed that these two types of pretreatments could improve PLB induction remarkably. After the explants were cut transversely twice or stabbed 15 times on different sites, their PLB induction rates went up to 66.1% or 68.3%, the PLB number per explant went up to13.1 or 15.2. After the explants were incubated in 0.4 mg·L^-1 mannitol solution or AAM medium for 2 hours as high osmotic pressure pretreatments, the PLB induction rates went up to 55.2% or 51.3%, the PLB number per explant went up to 13.7 or 12.9. While the PLB induction rate of the control was 19.5% and the PLB number per explant was 3.1. Compared with the control, the PLB induction rate and PLB number per explant were both significantly higher in all the pretreatments. Moreover, after the explants were pretreated by wound or high osmotic pressure, the time of PLB formation was 10 or 5 days shorter respectively than that of the control. However, there were not obvious differences between the first and second leaf explants in PLB induction. PLB induced from the explants that had been pretreated by wound or high osmotic pressure could develop into plantlet normally.

Key words: Phalaenopsis, Leaf, Pretreatment, PLB induction