The way a tomato plant grows depends on how a farmer mulches and fertilizes it, say researchers from the U.S. Department of Agriculture. They’ve uncovered some unexpected details about the biochemistry that goes into producing the juicy red fruit.

These photos show two fields of Sunbeam tomatoes planted at the same time and photographed on the same day. Tomatoes with black plastic around the plants and given standard doses of fertilizer (left) developed more leaf disease and aged faster than the sa

Dave Clark, Agricultural Research Service, U.S. Department of Agriculture

To cut down on weeds and make plants grow more quickly, farmers and gardeners often put black plastic around their tomato plants. Instead of plastic mulch, however, some growers have long preferred to use a type of plant called vetch as mulch.

Over the winter, the farmers grow hairy vetch, which belongs to the bean family. When springtime comes, they mow the vetch and plant tomatoes in the cuttings. The vetch keeps weeds out and nutrients in. Some research has shown that tomatoes last longer and get fewer fungal diseases when grown in dried vetch.

To understand why the system works so well, the researchers first compared two fields of tomatoes. One field got a mulch of vetch and a half dose of fertilizer. The other field got a mulch of plastic and a full dose of fertilizer.

In years with enough rain, tomatoes in the plastic-mulched field began to grow a little bit sooner. But vetch-mulched fields yielded a bigger, healthier crop.

Then, the researchers compared specific genes and proteins in the two crops. In the vetch-mulched plants, they found higher activity in two genes that help protect the plants from fungal attacks and two genes that control how the plants age.

Vetch-mulched tomatoes end up with especially big root systems. So, the researchers suspect that these plants are better at extracting nutrients from the soil. Better nutrition could affect how certain genes work.

Spaghetti sauce anyone?—E. Sohn

Going Deeper:

Milius, Susan. 2004. Plastic vs. plants: Mulch method changes tomato’s gene activity. Science News 166(July 10):21. Available at http://www.sciencenews.org/articles/20040710/fob5.asp .

You can learn about growing more and better tomatoes at www.ars.usda.gov/is/tom/ (Agricultural Research Service, U.S. Department of Agriculture).

Comments:

I love tomatoes. I eat them raw every day. It’s good to see appreciation for
tomatoes.—Brittany, 14

Mad cow disease gets its name because cattle infected with it behave strangely. They seem nervous and distressed. They can’t stand or walk properly.

Mad cow disease causes cattle to behave strangely.

These symptoms are caused by the breakdown of the animal’s nervous system. Deformed proteins, known as prions, multiply and worm their way through an infected cow’s brain and nerves, making the tissue look like a sponge.

These prions have a similar effect in people. They can cause the fatal human disease known as variant Creutzfeldt-Jakob disease (vCJD). Eating infected beef is the only known way for the prions to go from a cow to a person.

Consuming infected meat is also the main way prions are transferred from one cow to another. This can happen because of an old method of producing food for cows. When cows were slaughtered for their meat and hides, some of their remains—including their brains, eyes, spinal cords, and intestines—used to be processed to make animal feed containing protein.

This type of feed was banned in 1997 when scientists realized that it was responsible for the spread of mad cow disease.

Christl Donnelly of Imperial College in London says that as long as the ban on this type of feed is enforced, mad cow disease shouldn’t spread in the United States. This means it’s also highly unlikely the disease would spread to people.

Officials at the U.S. Department of Agriculture are taking an extra precaution. They’re planning on tracking every cow that will be used for beef, from its birth until it ends up in the grocery store.—S. McDonagh

Going Deeper:

Harder, Ben. 2004. Cow madness: Disease’s U.S. emergence highlights role of feed ban. Science News 165(Jan. 10): 19-20. Available at http://www.sciencenews.org/20040110/fob2.asp .

Milius, Susan. 2003. Mad cow future: Tests explore next generation of defenses. Science News 163 (May 31): 340. Available at http://www.sciencenews.org/20030531/fob3.asp .

Raloff, Janet. 2003. Calling all cows. Science News Online (Oct. 4). Available at http://www.sciencenews.org/20031004/food.asp .

You can learn more about mad cow disease at kidshealth.org/kid/talk/qa/mad_cow_disease.html (KidsHealth for Kids) and faculty.washington.edu/chudler/bse.html (Neuroscience for Kids).