Breeding perennial wheatgrass
Next phase of research will take agronomics as a starting point.
September 10, 2021 By Julienne Isaacs
Perennial intermediate wheatgrass is a multifunctional crop that may as well come straight out of a fairy tale: it’s a hardy, soil-building option for producers that returns reliable yields for food grain and forage year after year.
At the University of Manitoba’s plant science department, breeder Doug Cattani has been working to develop Prairie-friendly intermediate wheatgrass (IWG) cultivars for the last decade.
One cultivar has begun its final stages: Cattani and his colleagues will gather breeder seed from a site near Carman, Man., this year, after which Cattani’s team can start to increase foundation seed. Within just a few years, producers should have access to seed for planting.
IWG was introduced to North America in the 1930s, Cattani says, but work on the crop was predominantly done in Alberta or Saskatchewan, where winterkill limited utility.
When he began the project, Cattani’s goal was to evaluate genetic materials that had been developed by The Land Institute in Salina, Kansas, over three cycles of selection.
“It took three harvests to ensure two things: that the plants were adapted to Manitoba’s very harsh environment, and that they could be productive over that period of time,” he says.
Once they’d ensured survival and productivity, Cattani’s team made crosses, increased seed and began evaluating it for agronomics. The result is the first University of Manitoba IWG cultivar.
There’s been a lot of interest in the cultivar, Cattani says, mainly from organic grower groups, for whom it represents a high-value option for food grain, but also from research groups across the Prairies, who are testing the cultivar’s regional performance alongside partner producers.
This as-yet unnamed cultivar is only the first. Cattani’s program has begun the next cycle of selection. But they’re taking it slow.
“We wanted to figure out the agronomics first,” he explains. “We’ll use the agronomics to inform the next selection process. The practices we use and our selection process influence what we get out of it at the end.”
For instance, fertilization: Cattani says that when you’re selecting for wheat and fertilizing at the recommended rate, you look for the materials that perform best.
“Instead of getting 10 per cent of your population that’s adapted to lower N, by expanding and going to a higher rate, you’re opening it up to a group that may comprise 30 per cent of your population,” he says.
“We have to get something adapted to see how it grows here, and what are its greatest influences, and then enhance that to get better surviving, higher yielding populations.”
The main agronomic considerations for IWG are N fertility rates and timing, Cattani says.
“Depending on the plot locations, we’re using mono-ammonium phosphate and urea as N sources and seeing whether it needs N right after harvest, or whether it’s better first thing in the spring?”
The last experiment looks at whether a split application influences seedhead numbers. Because density is determined during vernalization the previous fall, with seedhead growth following in the spring, a fall/spring split application may influence yield.
“We’re trying to work out those components of production, and then we can inform producers what they need to do,” he says. “We’re trying to figure out where it fits into the overall scheme of perennial grass production. This will all be part of the marketing of the variety. And we can add what’s worked well for our producers in the past.”
IWG yields a lot lower than its annual counterpart, in the range of 40 to 50 per cent that of annual wheat, but it has many other benefits that could make it an attractive option for both conventional and producers.
While seed production is lower, producers may get five to six years out of a single crop before the need to reseed arises.
The benefits of the system for the soil are formidable: they include improved carbon sequestration and air and water infiltration, and better soil structure overall. Because live root systems are active through the year for multiple years, the plants can capture far more moisture and nutrients, making the crop – and the land – more resilient. After the second year, the crop shades out weeds, minimizing the need for herbicides under conventional production.
At the very least, the crop could be used as a soil remediation strategy for severely eroded areas, Cattani says. “It’s not going to cure all problem areas, but over time it can reduce the impact annual crop production is having on our soils,” he adds.
In one Minnesota study, IWG was able to capture nitrates leaching into the groundwater. In another study in an artificial environment the root system of an IWG crop was measured at 22 feet deep; even under normal field conditions, the root system can easily reach two metres by the end of the second year, Cattani says.
Winter survivability has been very good on the Prairies – Cattani says a bigger potential stress on the crop is late spring frosts after a good period of growth. “The plants de-acclimate when there’s no frost. A frost after a week or two of warmer weather, and we’ve lost plants. What we’ve ended up doing is selecting plants that begin regrowth later in the spring – that’s the adaptation part,” he says.
IWG won’t pay for itself in the first year, because the first year is considered a “juvenile” year and producers won’t see many seedheads. Cattani’s team has another study looking at establishment methods, such as spring seeding or underseeding to wheat. The first year’s data of the study shows that seed yield was not affected by underseeding to wheat in the first year – so producers could get an annual crop off in the first year and be ready to go in the second.
Cattani’s program has looked at other possibilities for improving value for the farmer, including intercropping with legumes for a long-term N fertilization solution, and livestock integration; both methods can be successful.
Cattani’s breeding program actually “weeds out” material that expands and yields well in the first year, because these tend to perform less consistently later on. And consistency is important for this crop.
“You want a plant with a large seed that produces year after year after year,” he says.
All of this takes time, from a breeding standpoint. “We’ve got to remember we’re 60 years behind canola breeding and 5,000 years behind wheat breeding. Once we get a good understanding of how the plant grows and its production, it’ll be faster. But patience is a virtue,” he says.