Stalk lodging

Daniel Robertson, University of Idaho assistant professor of mechanical engineering, helps workers in India husk corn.

Gains to farm revenue and the world’s food supply could result from even a small reduction in “stalk lodging,” a researcher says.

Lodging refers to stems breaking, causing them to lie flat and the ground and making them difficult to harvest.

“My goal is to reduce stalk lodging by 1 percent in the U.S. in corn, which would produce an extra $2 billion worth of grain every year,” Daniel Robertson, assistant professor of mechanical engineering at the University of Idaho, said in an interview. “Stalk lodging in corn is a multi-billion-dollar problem each year in the U.S., but if you look globally at the economic cost of stalk lodging in corn, wheat and rice — two-thirds of the world’s caloric intake — it is a trillion-dollar-a-year problem.”

Robertson, with UI colleagues and researchers at the University of Kentucky and Clemson University, are working to breed plants with stronger stems as part of a recently started four-year study that aims to increase grain yields and reduce crop loss. Plant scientists, engineers and mathematicians from the universities are working on the project, funded through a $6 million Established Program to Stimulate Competitive Research grant from the National Science Foundation.

Lodging is a serious problem in most grain crops, and results in annual yield losses of around 20 percent, UI said in a news release. Causes can include high nitrogen levels, storm damage, disease and seed type.

By measuring stalk strength and using mathematical modeling, researchers are investigating the microstructure of large plant populations to predict the underlying features that cause, and may be used to overcome, stalk lodging, UI said.

Robertson and UI renewable-materials chemist Armando McDonald are studying stalk lodging in corn and sorghum in an effort to breed stronger plants, the university said. McDonald is investigating stalk cells’ chemistry and cellular mechanics, and how changing plants’ cell walls affects stalk strength and deformation. Corn geneticist Rajan Sekhon and statistician Chris McMahan at Clemson are providing research.

Lead researcher Seth DeBolt, a University of Kentucky horticulture professor, said the team is taking a bio-mechanical approach. He said that by using bio-mechanical devices Robertson has been developing to rapidly measure stalk strength in the field, researchers will determine the lodging resistance of corn and sorghum varieties and in turn use engineering, math and statistical methods to predict why certain varieties are stronger or weaker. 

They especially want to determine genetic and environmental factors that influence stalk strength. 

“So far, we have found there is a systematic weakness in the corn plant,” Robertson said in an interview. 

“If you look at corn anywhere in the world, and where it breaks when it lodges, it looks the same,” he said, breaking 3 to 5 centimeters above a node line and falling in the direction of the smaller, or minor, axis relative to the plant’s cross-section oval. “To us as engineers, that’s the equivalent of a car’s transmission always going out at 40,000 miles. You know something is wrong with the system. The plant itself has inherent structural weakness.

“Now we can start breeding programs to eliminate that structural weakness,” Robertson said. “Plant breeders need a way to measure structural weakness and quantify it so they know what to breed for."

Compared to corn, sorghum will be more challenging in that the occurrence of stalk lodging appears to be much more variety-dependent, he said.

field reporter, SW Idaho and SE Oregon

Recommended for you