PHOENIX, Ariz. — According to superstition, a four-leaf clover brings good luck. Wouldn’t it be nice to be able to grow your own whenever you wanted? A 17-year-old researcher from Japan has found a way to do just that.
The shamrock, maybe the most familiar type of clover, belongs to two species in a genus called Trifolium. That name, which comes from Latin, means three leaves. And it well describes this plant. Only one shamrock in every few thousand has more than three leaves, notes Minori Mori, a 12th grader at Meikei High School in Tsukuba, Japan.
Some companies sell clover seeds that will grow into plants that are more likely to produce four leaves. But even in plants grown from these seeds, four-leafed ones remain rare. Minori wondered if she could somehow boost the odds of getting four-leafed clovers.
The teen showcased her success here, this week, at the Intel International Science and Engineering Fair, or ISEF. This competition was created by Society for Science & the Public. (The Societyalso publishes Science News for Students.) The 2019 event, which was sponsored by Intel, brought together more than 1,800 finalists from 80 countries.
Four-leaf clovers are most likely to show up in well-fertilized soil, Minori notes. She also knew that a hormone called auxin plays an important role in plant development. She decided to test how auxin and phosphates (an ingredient in common fertilizers), affected the chance of getting four-leafed clovers.
She ordered some of those special white clover seeds (Trifolium repens) and then grew them under a variety of conditions.
Agricultural research has shown that farmers who grow clover should use about 10 kilograms (22 pounds) of phosphate for each 40,000 square meters (10 acres) of farmland, says Minori. But she would be growing her seeds in plastic bins that measured only about 58.5 centimeters (23 inches) long and 17.5 centimeters (7 inches wide). She calculated that would translate to 58.3 grams (about 2 ounces) of phosphate per bin.
She added that amount to some of her bins. Some of these made up her control group, meaning they were grown under normal conditions. The teen added double the normal amount of phosphate to other bins. The seeds in some bins with each dose of fertilizer were watered with a 0.7 percent solution of auxin throughout the 10-day experiment. The others got plain water.
In her control group, 372 of the seeds matured into clover plants. Only four (about 1.6 percent)had four leaves. Two more had five leaves.In bins getting double the normal amount of phosphate but no auxin, 444 of the seeds sprouted into plants. And of these, 14 (or about 3.2 percent)had four leaves. So the extra phosphate doubled the share of shamrocks with more than three leaves.
If terms of four-leaf clovers, adding auxin didn’t seem to help much, Minori found. Only 1.2 percent of the seeds grew into four-leafed clovers if they were fertilized with a normal amount of phosphate and received auxin. That’s a slightly smaller share than in plants that got no auxin. About 3.3 percent of the plants that received both extra phosphate and auxin(304 in all) developed four leaves. That’s almost the same fraction as those receiving double phosphate but no auxin.
Where auxin did make a difference was in encouraging plants to grow more than four leaves. In bins fertilized with both auxin and a double dose of phosphate, a total of 5.6 percent grew more than four leaves. These included 13 with five leaves, two with six leaves, and one each with seven and eight leaves.
“Four-leaf clovers are considered lucky in Japan,” says Minori. “But clover plants with more leaves than that should be considered extra lucky!”
Power Words
More About Power WordscontrolA part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. For example, if scientists were testing different types of fertilizer in a garden, they would want one section of it to remain unfertilized, as the control. Its area would show how plants in this garden grow under normal conditions. And that gives scientists something against which they can compare their experimental data.
crop(in agriculture) A type of plant grown intentionally grown and nurtured by farmers, such as corn, coffee or tomatoes. Or the term could apply to the part of the plant harvested and sold by farmers.
development(in biology) The growth of an organism from conception through adulthood, often undergoing changes in chemistry, size and sometimes even shape.
engineeringThe field of research that uses math and science to solve practical problems.
fertilizer(v. fertilize) Nitrogen, phosphorus and other plant nutrients added to soil, water or foliage to boost crop growth or to replenish nutrients that were lost earlier as they were used by plant roots or leaves.
genus(plural: genera) A group of closely related species. For example, the genus Canis — which is Latin for “dog” — includes all domestic breeds of dog and their closest wild relatives, including wolves, coyotes, jackals and dingoes.
high schoolA designation for grades nine through 12 in the U.S. system of compulsory public education. High-school graduates may apply to colleges for further, advanced education.
hormone (in botany) A chemical that serves as a signaling compound that tells cells of a plant when and how to develop, or when to grow old and die.
Intel International Science and Engineering Fair(Intel ISEF) Initially launched in 1950, this competition is one of three created (and still run) by the Societyfor Science & the Public.Each year now, approximately 1,800 high school students from morethan 80 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of almost $5million in prizes.
phosphateA chemical containing one atom of phosphorus and four atoms of oxygen. It is a component of bones, hard white tooth enamel, and some minerals such as apatite.
speciesA group of similar organisms capable of producing offspring that can survive and reproduce.
square(in geometry) A rectangle with four sides of equal length. (In mathematics) A number multiplied by itself, or the verb meaning to multiply a number by itself. The square of 2 is 4; the square of 10 is 100.
Society for Science & the Public (SSP) A nonprofit organization created in 1921 and based in Washington, D.C. Since its founding, the Society has been promoting not only public engagement in scientific research but also the public understanding of science. It created and continues to run three renowned science competitions: the Regeneron Science Talent Search (begun in 1942), the Intel International Science and Engineering Fair (initially launched in 1950) and Broadcom MASTERS (created in 2010). The Society also publishes award-winning journalism: in Science News (launched in 1922) and Science News for Students (created in 2003). Those magazines also host a series of blogs (including Eureka! Lab).
About Sid Perkins
Sid Perkins is an award-winning science writer who lives in Crossville, Tenn., with his wife, two dogs and three cats. He enjoys cooking and woodworking, and he really, really wants to get better at golf.
