Fig. 1. Experimental set-up: HV — a.c. high voltage transformer, high voltage electrode —
array of 13 copper wires (diameter 100 μm, length 44 mm, distance between adjacent
wires 6 mm), ground electrode — aluminium tape (length 90 mm, width 48 mm), glass
plate (length 120 mm, width 90 mm, thickness 1.5 mm), and seeds — Triticum aestivum
(private collection).