Plants respond to light with a complex variety of reactions that are affected by the duration (photoperiod), intensity, and wavelength of the light. During the 19th century, Edward Babbitt and others reported that the germination of seeds increases by 50% under the influence of blue light (provided by blue glass filters). Plant vitality is increased, growth is accelerated, stem and leaf development are improved, and yields are increased.

In 1861, General A.J. Pleasanton constructed a 2,200 sq ft greenhouse in which every eighth pane was blue. Pleasanton obtained phenomenal results in terms of increased yields, improved flavor, etc, and he received US Patent # 119,242 for "Improvements in Accelerating the Growth of Plants and Animals." He recommended a ratio of white 8:1 blue light for optimal plant growth, and a ration of 1:1 for best animal development. Blue light stimulates the directional response of plants to light. Plants' pores open more widely in the presence of blue light (use it with Sonic Bloom). Evaporation and photosynthesis are intensified and chlorophyll production is accelerated. However, some cells may rupture, and mitosis may be inhibited.

The He-Ne laser (632.8 nm) can influence the phytochrome-controlled germination, growth and development of plants from a distance of more than a quarter-mile. The maximum effect is obtained by  only 1 or 2 minutes of exposure to reflected laser light. More than 10 minutes of irradiation will inhibit the phytochrome response. In some cases, successive nightly irradiations of low intensity have a significantly greater effect than a single exposure of greater length or intensity. The response can be reversed by alternating exposure to laser and infrared light. (30-32)

G. Krustev, et al., investigated the effect of laser irradiation on hemp production, and determined that laser treatment improved the sowing qualities of the seeds, shortened the phases of plant development, produced more vigorous plants, and increased the yields of both stems and seeds to a considerable extent. The researchers used a He-Ne laser for 15 and 30 minutes, and a nitrogen laser with 225 and 450 impulses. (33)

Red light can be used to increase the growth of some plants (beans, etc.) up to ten times the normal rate by stimulating phytochrome activity. Red light at 660 nm stimulates growth, development, flowering, and fruiting. When red light at 700 nm is available with 650 nm red light, photosynthetic activity is considerably greater than with either single frequency. Blue light at 420 nm enhances the effect of 650 nm red light. Photosynthesis occurs at approximately 440 nm.

Photosynthesis can be increased up to 400% by means of intermittent light. The researchers used a rotating disk with a cut-out section to chop the light from a lamp. They found that 75% of the light from a given source could be blocked without decreasing the rate of photosynthesis. The improved yields produced by intermittent light depends on the frequency of the flashing. A frequency of 4 flashes/minute resulted in 100% increased yields. The amount of work done by the light can be increased by shortening both the light and dark periods. For example, yields can be increased 100% by using 133 flashes/second. Emerson and Williams improved the yield (compared to continuous light) by 400% by using only 50 flashes/second. The light flashes must be much shorter than the dark period. The minimum dark period is about 0.03 at 25^o C. The light reaction begins with about 0.001 second/flash, and it depends on the concentration of carbon dioxide.

A. Shakhov, et al., developed several methods of applying Concentrated Pulsed Sunlight (CPSL) to stimulate the photoenergetic activity of seeds and plants. The flashes of CPSL last from 0.2 to 1 second and produce significant effects on physiological processes and increase plant productivity. The CPSL effect is not caused by the thermal action of concentrated light, but by endowing plants with a "photoenergy reserve" that increases yields of vegetable crops by 20-30%, and grain crops by 5-10%.

Arrays of aluminum and glass dishes are used to concentrate sunlight up to 100 times. The apparatus is shaken lightly by various means to pulse the irradiation as it is directed on seeds or plants. In one such device, a large semi-conical aluminum reflector is rotated by a motor at 100-130 rpm. The seeds arrange themselves in a single layer on the wall of the pan and receive intermittent irradiation as they pass through a fixed focal spot on the inside wall. Artificial lighting (70,000 lux) pulsed 120 flashes/min. was found to produce effects even though the light energy was much lower than that of CPSL. With duckweed, maximum growth was obtained with a pulse period of 0.004 second.

Another system uses tinted mirrors to produce single colors. S.A. Stanko irradiated soy plants with pulsed red light for 30 min/day for a week, resulting in a 8% increase in the protein content of the beans.

Thomas G. Hieronymous discovered that a plant can be grown in complete darkness indoors if it is connected by an insulated wire to a large metal surface that is exposed to sunlight. The plant must be at least 6 feet above ground and insulated to generate a voltage potential or antenna effect. The optimal size of the metal sheet must be determined by experiment so as to avoid sunburn (too large) or yellowing (too small). Plants cultivated in this manner will develop normally, while control plants will be stunted.

Dr. Wilhelm Reich (of Orgone fame) also found that plants could be grown without light if they were grown with magnetite that had been exposed to sunlight. The magnetite absorbs and reradiates solar energies that are utilized by plants.