Crop Tech Corner

High Carbon Dioxide Plus Drought Equal Bad News for Crops

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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(DTN photo by Nick Scalise)

ROCKVILLE, Md. (DTN) -- This bi-monthly column condenses the latest news in the field of crop technology, research and products.

NO SILVER LINING FOR CLIMATE CHANGE AFTER ALL

Higher levels of carbon dioxide have long been viewed as the one beneficial side effect for crops facing a warming climate. Now a new study from the University of Illinois suggests that even high levels of CO2 won't help plants if -- as expected -- droughts become more frequent and severe in the future.

"If you read the most recent Intergovernmental Panel on Climate Change reports and if you read the scientific literature on the subject for the last 30 years, the concluding statement is nearly always that elevated carbon dioxide will ameliorate drought stress in crops," University of Illinois plant biologist Andrew Leakey said in a university press release on his study. The scientific logic behind this conclusion was pretty sound: Carbon dioxide boosts plant growth in general, and high levels of it shrink leaf pores, which should limit moisture loss and water use. In fact, for four years, Leakey's own experiments validated this thesis. But those four years were relatively wet ones. "When the growing seasons were hot and dry, that pattern broke down," he said.

Using a university facility known as the Soybean Free Air Concentration Enrichment facility (SOYFACE), Leakey found that in hot and dry conditions, soybean plants exposed to higher CO2 levels used more, not less, water. Basically, the plants were setting themselves up for failure early on. They took advantage of the extra carbon dioxide to grow more aggressively and produced a bigger plant that they ultimately could not support when drought conditions set in, Leakey explained. The higher CO2 levels also encouraged plants to pack on nitrogen-fixing nodules -- but in shallow soil depths. Once the soil around them dried out, the nodules did not perform well, Leakey noted.

The results of his study have pushed Leakey to a grim conclusion. "All of the model predictions up to this point were assuming that in 2050, elevated CO2 was going to give us a 15% increase in yield over what we had at the beginning of this century," he said. "And what we're seeing is that as it gets hotter and drier, that number diminishes to zero. No gain."

For more information, see the press release here: http://bit.ly/…, and Leakey's study here: http://go.nature.com/….

WHEAT GETS A "FITBIT," BECOMES OBSESSED WITH ITS DAILY STEPS

Turns out people wearing Fitbits, the popular wristband activity trackers, have a lot in common with plant breeders. Fitbit devotees are essentially phenotyping themselves, that is, collecting data on physical signs of their health such as heartbeat and physical activity, noted a Kansas Wheat press release. Now Kansas State University wheat breeders have taken a cue from these health-obsessed modern Americans and produced a small, mobile, easy-to-use monitor for phenotyping wheat trial plots.

According to the release, the scientists have dubbed the new tool a Phenocart. Like the humble form of a Fitbit, which mimics the appearance of a watch, the Phenocart consists of a single bicycle wheel connected to a small platform with handles. Depending on the type of data desired, breeders can attach a variety of sensors to the Phenocart. The KSU scientists have selected sensors that measure the vegetation index, or "green-ness," of the plants in their plots, a leaf temperature thermometer and a GPS system. The scientists simply roll the Phenocart along the rows of the wheat trial plots, and it collects and processes the data as it goes.

"We really wanted something that we could pack up and take anywhere in the world," KSU crop scientist Jesse Poland said in the press release. "We've got lots of international partnerships, and we want it to make an impact across the global plant breeding community."

For more information, see the Kansas Wheat press release here: http://bit.ly/….

PIONEER FORGES AHEAD WITH GENE EDITING

Earlier this year, a DuPont Pioneer waxy corn hybrid made history by becoming the first agricultural crop produced by the gene editing tool CRISPR-Cas9 to be deregulated by USDA. Now the company has announced the development of a second corn trait produced with the new technology, which allows scientists to cut, copy and paste gene sequences within a plant's DNA. This time, Pioneer scientists used CRISPR-Cas9 to alter the expression of a gene, ARGOS8, that regulates the plant's response to water stress. The resulting corn hybrids "increased grain yield by five bushels per acre under flowering stress conditions and had no yield loss under well-watered conditions," the Pioneer scientists concluded in their study. "These results demonstrate the utility of the CRISPR-Cas9 system in generating novel allelic variation for breeding drought-tolerant crops."

For more information, see the study here: http://bit.ly/….

Emily Unglesbee can be reached at emily.unglesbee@dtn.com

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Emily Unglesbee