Engineering Stronger Crops
Douglas Cook analyzes a corn stalk in his lab.

Engineering Stronger Crops

"Geneticists have had a lot of success with corn," said Douglas Cook. "The kernels are bigger, the ears are bigger, the yields are bigger."

And yet there's a hint of concern in his voice: all that corn is heavy, and too often the plants' stalks buckle, dooming the plant. Cook, an assistant professor of Engineering at NYU Abu Dhabi, is working at the interface of crop science and engineering to solve the problem.

It is a costly one: Zea mays, commonly known as maize or corn, is the world's leading grain crop, but between 10 percent and 20 percent of what's planted is lost to stalk collapse, he said. Reducing the failure rate by just one percentage point, he adds, could increase the annual value of the global crop by USD 2 billion.

Breeding for bigger, sturdier stalks, Cook said, would be "the easy answer but the dumb answer" because that would take nutrients away from the kernels, the plant's payload. Left to itself, Zea mays might solve the problem through evolution, but that would be "slow, sloppy, and wasteful…we don't have time to wait for an evolutionary solution." He prefers the engineering approach: analyze the problem to create an intelligent solution.

But corn stalks are not nearly as uniform as, say, steel beams. And the load they must carry depends not only on the plant but also on weather and many other factors difficult to quantify. "You can predict everything about a bridge," Cook said, "because the geometry, the materials, and the loading are well known. But with biological systems everything is variable."

 

You can predict everything about a bridge because the geometry, the materials, and the loading are well known. But with biological systems everything is variable.

Douglas Cook, NYUAD assistant professor of Engineering

So traditional engineering methods alone are not sufficient. Instead, Cook's team at the NYUAD Biomechanics Laboratory is using x-ray CT scans and mechanical tests to measure the geometry and material properties of corn stalks. This data is then used to create hundreds of computational models of stalks, "virtual specimens" that are randomly generated to mimic the variation patterns seen in nature. The resulting "cloud" of data will be analyzed to pinpoint how the corn stalk can be modified, through breeding, to optimize strength.

Cook has already learned important things by examining broken stalks in Iowa, the heart of America's corn belt, where he goes every summer: failures are almost always at the "knuckles," the nodes between stalk sections. Between nodes, a corn stalk is slim and uniform, with a thin rind. But at the knuckles, both stalk and rind are thicker and denser. Engineers know that structural stresses can rise dramatically in regions where both geometry and material change rapidly, and this means trouble. The nodes are often too weak for the added stress imposed by fatter kernels and bigger ears. "A systemic failure means there's a systematic weakness," he said, "and I think we can fix it" — probably through simple selective breeding.

A solution is vital if yield per plant is to be further increased. And the work promises benefits beyond corn: wheat, rice, oats, bamboo, and bananas are all from the same family of plants, so an understanding of corn could be applied to other important crops as well. As food for people and animals, these are, Cook noted, "the foundation of the human diet." And he believes that what scientists learn about corn may prove useful in fruit and vegetable production, too.

Despite these alluring prospects, Cook said, little work has yet been done on crop biomechanics. There's been endless research on human-body biomechanics, and plenty of botanical crop science. There is even, he said with a hint of amazement, "a whole journal devoted to the study of wood." But "we've been reading the literature, and nobody has studied the biomechanics of corn."

So that is what Cook and his team are doing. The results may have broad effects for agriculture yields around the world.