Colored Plastics
Pretty is as pretty does.
You won't see colored
strips of plastic in the fields of Tennessee vegetable producers just because
they look nice. Plastic is an expensive item producers will buy only if
it earns its keep.
But plasticulture is a proven way to boost both yield and
quality, control certain insects and diseases, and help moderate soil temperatures
and soil moisture. Now UT researchers are evaluating the effects of color
on plant growth, soil temperatures, irrigation, weed control, and insect
control.
"Instead of just arbitrarily choosing a color of plastic,
we can choose a plastic that is going to give us relatively cheap control
of certain insects, or that will that have an effect on disease," said
Dr. Mike Buschermohle, an agricultural engineer with the UT Agricultural
Extension Service.
Colors used in the study include red, black, yellow, clear,
silver, and brown plastic.
"If we choose a darker color plastic, we're going
to get more heating, which can turn water into vapor. That vapor is going
to escape. Do we need to irrigate more with darker colored plastics? If
we go to brighter colors to get cooler temperatures, can we get by with
maybe irrigating a little bit less? When you consider costs of buying water
and the energy to pump it, you might be able to save money there. We're
also going to look at fruit set and yield to determine whether we're getting
more poundage-bigger fruit-just because we're manipulating that ratio of
far-red to red light reflected from the various colors of plastic."
But unfortunately, none of the plastics degrades during
a growing season and must be manually removed, which can be expensive. So
textile researchers from the UT Agricultural Experiment Station are helping
to evaluate the plastics, including a new one that is cornstarch based-a
plastic film made from residue of corn after you can't do anything else
with it.
"By the end of the year," he said, "we hope
to have enough information to say that selecting a plastic is more than
just 'the cheapest thing I can buy.' "
- by Lisa Byerley Gary | 