The bright sparks of electro-horticulture

Ever since Benjamin Franklin got his knuckles burned when flying a kite in a thunderstorm, many scientists — and even more quacks — have been curious about the possibilities of what has been called electro-horticulture.

The logic is inescapable — most things react in some way to an electric current. Why shouldn’t plants react too, and perhaps grow better/faster/bigger?

While I’m not prepared to speak authoritatively on this subject in general, I have had a bit of experience with one aspect of electro-horticulture: the use of electric lights — fluorescent lights to be precise — in a contraption intended to start seedlings indoors. It had three shelves illuminated by bulbs casting a special kind of light (I’m not sure how special it really was) and provided space for a couple of dozen seed trays. At the time I was working on the 29th floor of an office building, and inevitably the contraption ended up in the corridor outside the ladies’ room, which was the only place I could find to put it.

The plants didn’t seem to mind. In fact, under the benevolent rays of the Gro-Lux, watered from time to time and admired by most of my fellow office workers as they passed by, the infant courgettes, tomatoes, snapdragons and the rest thrived. If they resented the low status of their situation, they could at least look forward to being transplanted.

So far as I know, there is no particular controversy about the effectiveness of artificial light in growing plants. It works fine, and can be employed to good purpose even by those who, like me, are only modestly competent in technical matters. But the world of electro-horticulture involves more — and stranger — things than fluorescent tubing. This is where we get into the fun stuff, though, as we shall see, it’s as well to be careful.
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Apparently the first man to explore the potential was one Dr Maimbray (or Mainbray or Von Maimbray — sources differ) of Edinburgh who in 1746 undertook to electrify two myrtle bushes. He used a primitive electrostatic generator to produce the power. After being zapped for the entire month of October, according to Maimbray, the shrubs put out new branches and blossomed. A paper on the effects of electricity on vegetables read to the Royal Society in London the following year resulted in a wave of enthusiastic experiments, none of which seem to have come to anything. “The most striking feature of these experiments,” a historian remarked later, “is that they are always contradictory.”

He might have been speaking for succeeding generations of frustrated electro-horticultural researchers, because inconsistency appears to have dogged their efforts from the start. Triumphs were no sooner announced than failures followed. Nevertheless, work continued. The Abbé Pierre Bertholon, a French priest and pioneer electrical researcher, published De l’Électricité des Vegetaux, in which he described his method of spraying electrified water on growing crops from a special “electrovegetometer”, thereby encouraging them to grow. Results were ambiguous.

In Italy, less ambiguous results were obtained by a Dr Gardini, whose experiments in Turin backfired. Wire netting installed in the previously productive garden of a monastery there reduced its fertility to such an extent that the infuriated monks tore down the apparatus and ejected Dr Gardini. (In fairness, it must be said that Gardini could claim to have proved what he set out to prove — that plants deprived of atmospheric electricity by being covered with fine mesh metal cages would wilt and die. And so they had.)

Given the rudimentary understanding of electricity itself during this period, it is not surprising that scientific opinion about the way it might or might not affect plants was severely divided, if not fragmented. The great Alexander von Humboldt, in a work on plant physiology published in 1794, declared that there was scarcely any subject upon which learned men differed so profoundly. And if you did believe that electricity was important in horticulture, the questions about how and why crowded in. Did it increase fertility? Did it make atmospheric chemicals like nitrogen more available? Did it serve to break up soil particles? Did it make sap move faster inside the plants? What sort of electricity — static or voltaic — was most significant? The puzzles seemed endless.

Meanwhile, theories and experiments multiplied. For centuries farmers had sworn that thunderstorms make crops grow quicker. (Bertholon went so far as to blame the failure of the hop crop in 1787 to a shortage of lightning.)

Attempts were made to simulate or trap atmospheric electricity by stringing wires across fields or by erecting high antennae. One researcher maintained that this could be achieved by sticking a conical coil of stiff wire wound with nine turns (clockwise in the southern hemisphere, counter-clockwise in the northern) one foot north of a plant. Results, as usual, were mixed, with enthusiasts claiming success and sceptics the opposite.

In the 1840s there was a considerable stir. A Dr Forster, of Findrassie, near Elgin, reported that after stretching wires in particular directions over a crop of barley, he had produced a highly luxuriant crop. Fresh trials were projected all over Britain, even in the Royal Horticultural Society gardens at Chiswick. According to John Claudius Loudon, the premier gardening journalist of the day, “in all cases the result was a complete failure”. But then Loudon never was a believer.

What electro-horticulture did get was plenty of fashionable publicity. One especially delightful story tells of a demonstration conducted by the Marquis of Anglesey at a dinner party. (This noble lord is perhaps best remembered for his exchange with the Duke of Wellington during the battle of Waterloo. Anglesey: “By God, sir, I’ve lost my leg!” Wellington: “By God, sir, so you have!”) When the guests sat down they watched cress seeds being sown into flats containing a mixture of sand, manganese oxide and salt, the whole moistened with diluted sulphuric acid and electrified. Five hours later — it was a leisurely dinner — the cress was harvested and served up in a salad. At least that was the way the story went.

The years before the First World War saw the last real flowering of electro-horticulture, stimulated by the work and writings of several European experimenters. Most important was a Finnish scientist named Karl Selim Lenström, who noticed how rapidly and vigorously plants grew in the short Lapland summer and concluded that, as shown by the aurora borealis, it was because there was so much electricity floating in the Arctic air.

Lenström strung up current-carrying wires, first over pots and later over whole fields, finally concluding that electricity encouraged everything from parsnips to strawberries (though not turnips and tobacco).

The Great War did not bring electro-horticultural experimentation entirely to an end, but during the rest of the 20th century it was fairly desultory. The British Board of Agriculture and Fisheries set up an Electro-Culture Committee in 1918, which conducted a number of hopeful experiments before closing down, somewhat dejected, in 1936. Worst of all, occasional findings suggested that it might be better to avoid the whole sparky enterprise. When researchers at the Florida Agricultural Experiment Station ventured to see the effect of electrical current on ‘Estes’ rough lemon seedlings in 1975, they first found no effect. Then after a brief increase in growth, the issue was settled in a very final way. The trees died.

That may not, however, be the last word on the subject. In 2006 an English botanist named Andrew Goldsworthy came up with an ingenious explanation of why plants reacted positively to electrical current. It was, it seems, a hereditary response to the atmospheric electricity produced by an approaching thunderstorm. Being zapped caused the plants to anticipate a good drink of water and prepared them for making use of it — and growing faster.

The cutting edge of horticulture

1. Plant science is today a multi-billion dollar industry which funds research into all kinds of areas, including:

2. Drought-resistant cereals. Essential for feeding developing countries. The Bill and Melinda Gates Foundation hopes that its maize program will boost yields by as much as 30 per cent by 2016, helping up to 40 million people.

3. Bamboo is an up and coming plant. It absorbs huge amounts of carbon dioxide while growing and can be used in the production of renewable ethanol and diesel.

4. Genetic modification of crops to improve yields and disease resistance is slowly gaining acceptance. Last month the French courts annulled a ban on farmers growing a strain of GM corn.

5. Plastics derived from plant starches have real potential. When the starches are broken down in natural sugars they form plastics through a process of fermentation and distillation.

6. Modern apple varieties are being bred to fruit without pollinators, thus cropping more reliably.

The bright sparks of electro-horticulture – Telegraph

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