On a recent summer morning, a team of students and scientists worked quietly, row by row in a research field, thinning soybean seedling plants by hand and saving the strongest to establish a uniform plant population for varieties to be grown in a new research project.
The team, led by Kansas State University agronomy professor and soybean breeder Bill Schapaugh, is just starting work on a three-year effort to develop soybean varieties that will better withstand heat stress in the critical post-flowering stage of development. He is working with K-State associate professor and crop physiologist Krishna Jagadish and University of Missouri geneticists Henry Nguyen and Tri Vuong on the project.
The work is made possible by a $500,000 award from the U.S. Department of Agriculture’s National Institute of Food and Agriculture (USDA-NIFA).
“The long-term goal of this research is to strengthen the development of commercial soybean varieties with improved tolerance to heat stress,” Schapaugh said, adding that the specific goal is to identify and characterize unique sources of post-flowering heat tolerance in existing soybean germplasm that can be used to develop commercial varieties.
“We are focusing on post-flowering (the seed-filling stage of development) because environmental stresses, such as heat, tend to have the largest impact on seed yield and seed composition during this period of growth,” Schapaugh said.
High daytime temperatures during that stage of soybean development can negatively impact yield – or, how much grain a plant produces – and grain quality, which ultimately reduces what farmers have available to sell after harvest.
That’s particularly important because climate models are projecting that U.S. soybean growing regions will not only experience increased mean seasonal high temperatures, but also frequent episodes of high daytime temperature stress, Schapaugh said.
The researchers are laying the groundwork for developing new cultivars that can tolerate heat stress better than those currently available by accomplishing three objectives, including:
- Observing different cultivars’ yield and composition changes during induced heat stress through a process called phenotyping.
- Mapping genomic regions responsible for sustaining yield, seed quality and composition under post-flowering heat stress.
- Validating haplotypes – DNA characteristics that tend to be inherited together with the goal of strengthening breeding efforts to improve soybean resilience under post-flowering heat stress in the future.
To control how much heat and other environmental factors some of the plants are subjected to, the team will grow part of the soybean accessions in eight large tents. Others will be grown outdoors.
The heat tents are unique, custom designed structures placed over the plots that are covered with a clear polyethylene film, Schapaugh said. They resemble a clear wall tent. Air inside the tents will be heated from the sunlight and sensors, and electrically-controlled panels regulate the temperature within the tents during the day. Such heat tents have not been used routinely in soybean research but have been used in a similar manner by Jagadish’s team to examine heat tolerance in wheat.
As part of the research team, K-State and MU undergraduate and graduate students, plus a post-doctoral researcher are enhancing their own education and research skills and techniques, Schapaugh said.
In the end, he added, consumers will benefit from a more consistent supply and quality of soybean products.