This section is from the book "The Gardener's Monthly And Horticulturist V24", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
Translated for the Gardener's Monthly from the Berliner Tribune. BY S. M.
How much of human progress we would miss if we could not master electricity! As it is, space and time are almost annihilated, and electricity begins even to compete now with the sun. Night is transformed into day, and that time may not be distant when every steamer, crossing the ocean, will carry its electric sun to chase away the terrors of the night. In this line electricity seems likely in future to substitute the sun also for the field and the garden, and may attain an incalculable importance.
We have heretofore been told that the beneficent influence of alternating day and night on us mortals is effected both through the change from activity to rest, and from light to darkness Our eyelids would not droop so easily, and sleep would not be so refreshing if the stimulus of light were uninterrupted. We are likewise inclined to believe that the repose in darkness is necessary for plants, as though it were a rest from the stimulus of the light of day. Closely considered, we find that the change from day to night is after all but a relative one on our planet, and subject to the widest variations. On one hand, the constantly equal length of night and day under the Equator ; on the other hand, night of six months' duration at the poles, and all the gradations between. This would seem to prove that, as a general principle, the alternation of day and night would not be necessary for plants, and the investigations of Mr. C. W. Siemens, in London, would almost make sure that many plants at least not only can stand constant light, but will improve under it ingrowth.
As long as eighteen months ago, Mr. Siemens already published his experiments on the influence of electric light on vegetation, and they showed that its effects on plants were similar to-sunlight, that they formed chlorophyll (leaf-green) ; that, under it, blossoms and fruit, odoriferous and savory, were developed - in fact, that a periodical withdrawal of light during the twenty-four hours was not generally necessary, but that, on the contrary, many plants would grow stronger and richer if, in winter-time, exposed by day to sunlight, by night to electric light.
Since then Mr. Siemens has continued his investigations on a larger scale, and they claim so general an interest, that it seems proper to speak about them here, after his report read last September before the British Association.
Mr. Siemens used two electric lamps, worked by the currents of two electro-dynamic machines, each supplying the light of four thousand candles. One lamp was hung inside of a glass house of 2,318 cubic feet of space, over the entrance, and a metallic reflector was fixed before it for the purpose of collecting its rays and turn them on the plants, which otherwise would have lost them. The other lamp was hung in the open air, twelve to fourteen feet high over some low-situated glass houses. These experiments lasted from the 23rd of October, 1880, to the 7th of May, 1881. The electric light glowed from six in the evening, and, during the shorter days, from five in the evening. The only rest given the plants was during Sundays. There were peas, string beans, wheat, barley, oats, cauliflower, raspberries, strawberries, peaches, golden apples (tomatoes?) grapes, and some flowers, such as roses, Rhododendrons and Azaleas. The lamp in the open air had a glass shade, the lamp inside had none. The effect of the two lamps immediately showed a great difference. The plants under the first prospered exceedingly; under the second they soon got to look wilted.
But as soon as a thin colorless glass was fixed between the plants and the light the pernicious influence ceased - a remedy acting in wonderfully quick time. Again, if the glass was fixed so as to intercept the light only on some parts of the plants, leaving others exposed to the naked rays, the influence of protection and exposure showed itself in one single night, and very markedly. The exposed parts looked shrunk, the protected parts looked sound and strong. And not the leaves alone showed the marks of the destructive power, but also, though less markedly, the young stems showed them after they had been exposed to the open light at a distance of about twenty feet from it.
Now, why does that glass shade protect the plants? The really illuminating rays are not obstructed by it. Stokes, however, has shown, in the year 1853, that the arc of electric light is rich in those invisible rays of great frangibility, which are of ultra violet color, and also that the greater part of them is absorbed by glass. It consequently seemed as though these were the enemies of plants, whilst the illuminating rays of less frangibility would stimulate their growth. To arrive at greater certainty, Mr. Siemens planted mustard and other quickly germinating seeds, dividing the ground in equal radii, so that all the plants should be at an equal distance from the light. Part of them were exposed to the naked light, another part was covered with a pane of glass, a third with yellow glass, a fourth with red, and a fifth with blue glass. The relative development of the plants was noted down every day, and the differences were of a marked character. The plants under the colorless glass were strong and healthy beyond all the rest. Next came those, under yellow glass; they were as large as the former in size, but color and thickness of stem were less than in the former. The plants under the red glass were lanky, and their leaves had a yellow tinge.
Under the blue glass they were still more lanky, and the leaves looked sickly. The plants under the naked light were worst of all, looking very poor, their leaves very dark and partly shrunk. These results agree with those which Mr. Draper in the year 1843 obtained, in his investigations of the influence on plants of the different colors of the solar spectrum, viz., that it is principally the yellow rays which work the disintegration of carbonic acid in the cells of the plants, and not the violet rays, contrary to their usual chemical effect.
Mr. Siemens, after these experiments, put a glass shade round the electrical lamp, and obtained marvelous results. Peas, sown end of October, gave a ripe crop on the 16th of February. Raspberry plants, brought into the greenhouse on the 16th of December, had ripe fruit on the first of March ; and strawberries, planted at about the same time, bore ripe fruit of superior flavor on the 14th of February. Grapevines making shoots on the 26th of December, bore ripe grapes on the 10th of March, but these were more acid than usual. Wheat, oats and barley grew with tremendous rapidity, but did not ripen in proportion to their strength, they had grown too fast, and when twelve inches high had fallen to the ground. When sown out of doors, and exposed until beginning of May to the electrical light, hung in the open air, after having been sown on the 5th of January, and retarded in their growth for some time by snow and frost, they developed quickly as soon as mild weather set in, and had ripe grains end of June following.
The next experiment was to find whether, contrary to the doubts of botanists, such plants would propagate their kind. So peas, grown under the constant influence of the electiric light, and gathered on the sixteenth of February, were planted on the eighteenth of February. They came up in a few days and grew finely. However further requirements will be necessary to establish positive conclusions.
Now, although darkness seems to favor length of growth in stems, Mr. Siemens is of opinion, after experiments made in the course of two winters, that the continual stimulus of light calls forth an accelerated and sound growth of the plant through all its stages, from the first leaf to the ripened fruit. Moreover the fruit, thus obtained, is superior in size, aroma and flavor, and finally the seed in it will germinate and produce. A particularly strong influence had his light on a Banana plant, which was twice exposed to it, first during its first stage of growth, next during the stage of fruiting - February and March, 1880 and 1881 - and produced fruit weighing about seventy-five pounds, each banana of unusual size, and declared by connoisseurs of unsurpassed taste. Melons also succeeded remarkably and were of unusual size and aroma.
These experiments were not made to obtain results in the way of quantity, but to establish the influence which electric light had on plants generally. Nevertheless, Mr. Siemens thinks that it will not be long before electric light will be of great service to horticulture, inasmuch as it makes the gardener independent of climate and season; and, he adds, it might further lead to the production of new varieties. What he has obtained thus far, warranted him, he says, in obtaining better and better results, as soon as he learned the proper conditions of temperature and the proper strength of light applied. He will not let these experiments stand as mere curiosities, but he will try to make them practically useful to agriculture. Here, of course, the cost comes in and decides. To produce electric light a motive power is required, putting in motion a dynamo-electrical machine yielding the required electrical current. Where there is water power, the cost will obviously be small. But the cost of steam can also be reduced, if after having done its work for the dynamo-electrical machine, the steam were used to heat the greenhouses and saved fuel there; otherwise daylight would be equal to a positive loss.
Again, the electro-dynamic machine, used by night to produce electric light, could in the daytime be used to furnish power. The electrical current might be directed through wires to various points on the place and drive electro-dynamic machines for various purposes, such as cutting wood, pumping water, etc., perhaps also for threshing, mowing and ploughing. These things are now done by movable steam engines which require water and fuel all the time, and also a skilful and careful attendance, and are comparatively heavy. Electro-dynamic machines on the other hand are comparatively light and are simply fed through wires with electricity, produced at the central station, and there less fuel is necessary to produce steam than in the open field.
Thus electricity seems to claim a new field and a promising one in the development of our civilization.