Abstract: Applying an alternative electric field (sine wave, 500 KHz, 175–225 v/cm) generated from a self-made cell fusion apparatus, the mesophyll protoplasts of barley, (green or green and etiolated), broadbean or tobacco formed chain arrangement between two parallel electrods so that a very small area of the membranes of the protoplasts to be fused was brought into close contact. On the additional application of a single square pulse (10–40 μs, 800 v/cm, depending on the kind of protoplasts investigated), the reversible breakdown of plasma membranes was induced and then protoplast fusion was triggered. The protoplast fusion frequency was over 50%. The relation between square pulse and fusion percentage and other factors influencing fusion was discussed.

Key words: Electric field, Mesophyll protoplast, Fusion