The next step for plant researchers is identifying how different hybrid root systems work in actual field conditions. Root system shape and architecture are thought to be heavily influenced by environmental conditions.
The plant’s contribution from below ground is increasingly a focus to manage hybrids for maximum yield
Farmers know the importance of a good root structure for their corn plants, but do we know all there is to know on how roots contribute to yield?
From the lab to the field, new efforts are piecing together how knowing more about roots can lead to better management and higher yields.
Researchers at a USDA–Agriculture Research Service (ARS) laboratory are taking a 3-D approach to studying roots—literally.
Leon Kochian is director of the USDA–ARS Robert W. Holley Center for Agriculture and Health on the Cornell University campus in Ithaca, N.Y. His team has developed the RootReader 3-D platform, a root growth, imaging and analysis system that grows plants in cylinders with the roots growing in a gel or nutrient solution. The root systems are photographed on a computer-controlled rotating platform to capture 100 images as the plant is rotated 360°. The RootReader 3-D software automatically reconstructs the 100 2-D images into a 3-D view to measure the roots to better study their structure and architecture.
This sorghum plant is growing in a hydroponic cylinder system used for analyzing root systems with unique nutrient and stress regimes.
"Researchers and those in the seed industry are realizing that we need to know what root systems do. In our research, we score 20 different traits, including root length, thickness and angle, as well as traits that measure the shape and structure of the entire root system" Kochian says.
This three-dimensional platform was developed in 2007 and has been in use in its current setup since 2010. Kochian’s lab has studied rice, sorghum and corn.
"This approach allows us to look at the whole root system as it develops in the first 20 days
of growth," he explains. "In the architecture of the root system is a trait called centroid, which is the vertical position of the center of mass and a quantitative measure of the depth of the root system."
Gold down under. Knowing more about root structure and what goes on beneath the surface will lead scientists to a better understanding of the plant’s nutrient uptake ability.
"In the past, the focus has been on the plant’s characteristics above ground, but we’re interested in increasing the effectiveness of the below-ground root system to absorb nutrients," Kochian says. "One issue that has brought a lot of attention to this type of research has been the recent droughts and water shortages. But we can also look at how to improve the plant’s ability to take up phosphorus and nitrogen from the soil, based on its root structure."
Phosphorus is not a very mobile nutrient within the soil, so a plant that has more shallow roots will be able to capture phosphorus that resides in the top layer of the soil, Kochian notes. Conversely, deeper roots will be able to capture more nitrogen and water, which moves much faster down through the soil profile.
"We have been able to genetically map these traits and have found regions of the plant
genome where specific DNA sequences appear to control deep versus shallow and compact versus spread-out root structures," Kochian explains. "We don’t know what type of root system shape and architecture is important until we test in the field, but this system allows us to capture the foundation for that research. Genetics are an important part, but environment will also obviously always impact how roots grow."
Field studies. The known limitation of this lab research is the controlled environment—soil in the field can widely vary and impact root growth. To translate lessons learned in the lab to research in the field, seed companies are picking up the baton. Companies such as Beck’s Hybrids and AgriGold have expanded their research efforts focusing on roots.
"At Beck’s, we measure the roots according to what the farmer will see in the field," says Doug Clouser, product lead for the company. "Because the environment plays a significant role in the development and structure of roots, we look at the overall root strength when we’re evaluating a hybrid’s performance."
- Seed Guide 2013