Color

Article from the March 24, 1998 New York Times
Science Watch: A Shade of Difference
By Karen Freeman

For a plant protein that was dismissed by skeptics in the 1950s, phytochrome has come a long way. Because of it, growers who want the best and biggest tomatoes, strawberries and other crops need to be as fussy as an artist over the color of the plastic mulch they put in their fields. The protein directs plant growth and development in response to different kinds of light. And because of that, growers need to concern themselves with a color they cannot see, the far-red light that is just beyond the horizon of human vision, as well as the normal colors.

Green leaves reflect far-red light, so plants can be fooled into thinking that they have lots of neighbors - and competitors - if they are bordered by mulch that reflects plenty of far-red wavelengths. In response, the deceived plants put more energy into their above-ground growth, and that means bigger tomatoes or strawberries that mature faster. They taste better, too, said Dr. Michael J. Kasperbauer, a plant physiologist with the United States Department of Agriculture in Florence, S.C., who has been manipulating lights to manipulate plants almost since the existence of phytochrome was proved in 1959. A patented red plastic mulch developed by Kasperbauer and Dr. P.G. Hunt and manufactured by Sonoco is being sold to growers and gardeners.

Strips of plastic mulch have long been known to help conserve moisture in some situations, but now scientists' attention is on mulch colors - whites, yellows, blues and greens - to see how they can enhance things like flavor and insect control. Want a better root crop, like turnips? Pick a mulch color, like orange, that reflects much more red light and little far red. The plants, not fretting about competitors, put their resources into growing bigger roots. The possibilities seem endless. "It's kind of like being a little kid on a merry-go-round," Kasperbauer said. "It's too much fun to stop."