Deb Babcock's gardening column appears Mondays in Steamboat Today.
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Steamboat Springs In an effort to grow beautiful flowers, fruit and vegetables, we gardeners tend to coddle our plants. The second the soil is dry, wet water. If it looks like an insect is chewing on it, we apply insecticides. To control weeds, we use herbicides. And we apply fertilizers, and protective covers on cool nights, and all manner of protection to achieve a perfect, county-fair worthy specimen.
Well, now it's been scientifically proven - in February's "Science News" - that a little tough love will produce a more nutritious and more flavorful fruit or vegetable and perhaps a more aromatic, colorful flower. They may not look as good, and perhaps have a few holes in the leaves where insects have dined, but they are beautiful where it counts: inside.
According to a study by researchers at the University of California-Davis, crops that are not coddled, e.g. those that are grown organically, "far surpassed their conventionally grown kin for vitamins and beneficial micronutrients, such as the antioxidant flavonoids quercetin and kaempferol." Flavonoids have been shown to reduce high blood pressure which helps prevent heart attacks and stroke. There's also some limited research showing that flavonoids can help prevent certain types of cancer.
The nutritional value of a fruit or vegetable tends to fall into two categories: primary and secondary plant metabolites. The primary metabolites include the fats in the plant, carbohydrates, amino acids and sugars. Most of us are familiar with these nutrients since they are the ones usually listed on food labels.
Secondary metabolites have such unfamiliar names as carotenoids, alkaloids, phytosterols, saponins, sulphides and flavonids, among many others. These usually are present in our food in very low amounts since large commercial farming operations tend to concentrate their practices on maximizing the primary metabolites.
Secondary metabolites tend to be defense compounds in a plant, such as its natural pesticide, a detoxification agent or sun screen. (Or in the case of a flower, an odor or enhanced color to attract the right pollinator or repel a pest.) When a plant is not stressed, it doesn't tend to produce many of these compounds.
When food is grown organically, it tends to come under more stress since the pesticides and herbicides and fertilizers used by nonorganic commercial growers are not used. There are more pests that the plant has to deal with, weather-related stress that it's not protected from, and more effort has to be put into finding nutrients from the soil.
The result is a fruit or vegetable that might not look as good as those found in the grocery store (or at the county fair), but the nutritional value is higher. And another bonus: it tastes better because some of the secondary metabolites break down into flavor compounds.
So the next time you see an heirloom tomato in the produce section of your favorite shop, don't pass it by because of its unattractive looks. Give it a try. You'll love the taste and find it's better for you.
And in your own garden, consider letting your plants experience a little stress in an effort to make them more nutritious.
Deb Babcock is a Master Gardener through the CSU Extension Routt County. Questions? Call 879-0825 or log onto http://rcextension.colostate.edu