barley

Taken July of 2019 using the minirhizotron method, this photo shows the root system on a stay-green barley plant at the Northern Ag Research Center. 

The majority of farming in Montana is done on a dryland basis. That means that the success of those acres is wholly dependent on rain and the hope that it comes at exactly the right time. It is impossible to control the weather, but over the years, plant breeders have been trying to find ways to optimize water-use efficiency.

One such attribute, known as the stay-green trait, is self-explanatory. Cereal crops that possess this genetic variance stay greener, longer. Plants require water to be cycling through them in order to undergo photosynthesis. So, if water becomes a limiting factor, the plant will stop putting starch into grain and yields can be negatively impacted. 

“What we are seeing is, the stay-green lines are releasing more water at certain times. We think that means they have access to more water,” explained Dr. Jamie Sherman, barley breeder at Montana State University.

But why? And could the root system on plants with the stay-green trait have anything to do with it?

Sherman, along with grad student Jessica Williams and in collaboration with Dr. Maryse Bourgault at Northern Ag Research Center (NARC) in Havre, set out to dissect those two major questions using stay-green barley bred and developed at North Dakota State University. Sherman and Williams are photographing, examining and measuring the root systems of these plants at different stages of maturity.

“I’m trying to make some comparisons and see if there is a connection between early root growth and later root growth, and I’m also interested in comparing the stay-green plants with the non-stay-green plants,” Williams said.

Examining roots is no easy feat. In the greenhouse, Williams employees two different methods to photograph the roots. In one method, seeds are lined up on the top of germination paper, which is then rolled-up. The roots grow down the paper and once the plants are at the one-leaf stage (about 11 days old), Williams unrolls the paper and scans the roots.

In the other method, the plants are permitted to grow for about a month until they are in the four-leaf stage. The roots grow down a PVC pipe that is filled with Turface, a product commonly used on sports fields. Williams points out that Turface happens to be a great medium for growing roots and is easy to wash away from the roots when it comes time to photograph them.

Once out in the field, photographing roots becomes even more labor intensive. In barley fields at the NARC, four-foot long tubes made of clear fiberglass were placed in the ground at a 45-degree angle. These tubes, known as minirhizotron, remain in the field during the entire growing season, and as the roots grow, often some come in contact with one of the 48 tubes.

A cylindrical scanner was placed down each tube to photograph the roots, which Williams did twice, once when the plant was flowering and once when the plant and grain had reached maturity.

Preliminary data from this research is just that, preliminary, but already Sherman and Williams have made some interesting discoveries. There has always been a suspicion that the root system on stay-green plants had something to do with their special quality, but it has been unclear as to what that something is.

“I’ve taken an early look at our data and I believe, at least in barley, the stay-green lines make more roots right away. Maybe that helps them to establish a larger root system, earlier in the growing season when there’s more moisture available,” Williams noticed.   

Another potentially important observation is the angle at which the roots develop from the seed. Originally it was hypothesized that the roots on stay-green barley would come out at a narrower angle but grow longer so they could reach water deeper in the soil.

“It’s a little surprising actually, but our stay-green barley lines seem to have a wider root angle then our non-stay-green lines. It could mean they are branching out more and collecting water from a wider area in the soil,” Williams stated.

As a barley breeder, Sherman is hoping this research will eventually lead to the discovery of a genetic marker that can be isolated and then used to improve barley, especially for dryland producers.

“With a few more years of work, maybe we can start talking about what genes are involved in controlling the stay-green trait and root development,” Sherman said.

As answers come to light in the greenhouse portion of this research, more questions seem to develop out in the field. What was initially thought about the roots on stay-green barley, may not actually be what is happening.

As data continues to be analyzed, Sherman and Williams’ work has the potential to impact not only the barley industry, but all of cereal grains as well. Both researchers admit it is exciting to dive further into this process as they try to unearth what is going on below the surface of a barley field.

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