Strawberries grown on red plastic mulch are sweeter and more flavorful than conventionally grown berries, say scientists with the United States Department of Agriculture’s Agricultural Research Service.
Colored plastic mulches are already starting to appear in some horticulture supply centres. Earlier research has shown that tomatoes ripen faster with red mulch.
In this latest research, Michael Kasperbauer at the ARS’s laboratory in Florence, South Carolina, grew strawberries on raised beds covered with a specially formulated red plastic.
The scientists were able to keep the water-conservation benefits that are attributed to black plastic mulch while at the same time altering the amounts of far-red and red light that reached the developing berries.
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The light is reflected from the red mulch on the soil surface and acts through the plants’ natural growth-regulating system to influence the size and flavor of developing berries.
Strawberries that ripened over the red plastic mulch were larger and sweeter than those that grew over black plastic. They had higher sugar-to-organic-acid ratios and gave off higher concentrations of favorable aroma compounds.
Kasperbauer, who pioneered the use of colored plastic mulches, has found that the higher amounts of certain growth-enhancing wavelengths of sunlight reflected by red plastic mulch improve many crops, including tomatoes and basil.
Plastic mulches, most often black, are frequently used in raised-bed culture to conserve water, control weeds with less herbicide, keep fruit clean and produce ripe berries earlier in the season.
The research is scheduled for publication in the July issue of Photochemistry and Photobiology. The author’s manuscript is available on the web at www.ars.usda.gov/is/pr/2001/010430.htm.
