No. 54: Nov-Dec 1987
"Scientists have long known from laboratory experiments that various colors of light can affect stem size, root structure and other aspects of plant growth. But they have remained largely in the dark about the potential practical benefits of the phenomenon.
"Using colored mulch to bathe plants in reflected light of certain hues, the South Carolina group (Clemson University) has begun to explore what colors plants prefer in agricultural growing conditions. Last year, for example, the group found that tomatoes grown with red mulch -- made with plastic sheets painted red -- had 20% higher yields than those with black mulch. Preliminary results this year show that potatoes and bell peppers grow best with white mulch...."
(Anonymous; "Plants' Colors," Wall Street Journal, September 16, 1987. Cr. J. Covey.)
Comment. Many questions arise here, but we'll take only three: (1) How do plants sense colors? (2) How do different colors mediate growth differently? (3) Is all this explicable in terms of evolution?