CHAPTER FIFTEEN

The Quiet Years

After 1936 electroculture did not die. It became a minor specialty, pursued by scattered individuals who mostly did not know of each other, and several of them found things worth knowing.

Too much of a good thing

In the early 1960s Lawrence Murr, then at Pennsylvania State University, grew grasses and other plants between charged plates in the laboratory and published the results in Nature and elsewhere. He showed clearly what the old field workers had suspected: at high field strengths, plants are injured. The tips of the leaves, where the field concentrates, pass a discharge current, lose water, brown and die. Murr’s work established that there is a dose, and that above it electricity harms. Below the damage threshold he reported some stimulation, modest and variable.

Ions in the air

At the University of California, Albert Krueger spent years on the biological effects of air ions, the charged molecules that an electrical discharge produces. He reported that seedlings of oats and barley grew faster in air enriched with ions and more slowly in air stripped of them. This offered a possible mechanism for the overhead-wire effect: perhaps the plant responds not to the field itself but to the stream of ions it sets moving. In 1981 Herbert Pohl and a colleague, publishing under the old name “electroculture,” reported increased flowering in plants supplied with negative air ions.

A theory at last

The most interesting idea of these years came from Andrew Goldsworthy, a plant scientist at Imperial College, Blackman’s old institution. Goldsworthy asked why a plant should have evolved any response to electric fields at all. His answer was the thunderstorm.

For some time before rain, the electric field at the ground changes sharply. A plant that could sense that change, and respond by gearing up its metabolism to take advantage of the water about to arrive, would have an edge over one that could not. On this view the electroculture effect is real but is not a feeding of the plant. It is a false alarm: the wires imitate the electrical signature of an approaching storm, and the plant responds as if rain were coming.

The theory explains several stubborn facts at once. It explains why tiny currents work as well as large ones, since it is a signal and not an energy supply. It explains why the treatment helps well-watered crops and harms dry ones, since a plant tricked into rapid growth without water to sustain it suffers. And it explains the erratic field results, since the real weather is sending its own signals all the while.

It has not been proved. But it remains the most coherent account anyone has offered of why Lemström and Blackman might have seen what they reported.

Meanwhile, in China

One more development of the quiet years would turn out to be the most important. In 1990 the Chinese government began funding experiments with high-voltage electric fields in vegetable greenhouses. The work continued, with little notice abroad, for nearly three decades. We will come to its results in the next part, where the question at last is put directly.