Prairie ground is prone to salinity, but scientists are looking for crops that will offer new options
The western Canadian prairie has one thing in common with the well-groomed golf courses surrounding New Jersey’s Rutgers University: the need for stronger saline tolerant grass varieties.
On the Prairies, new grass varieties with greater saline tolerance could access and remove salty water locked within the soil. Grain growers would have better salinity control around borders of potholes and field edges, and the livestock industry would have an additional source of forage.
Golf courses are a different story. Rutgers, the prestigious Big Ten university, is working on turf grasses with greater saline tolerance. Not only will the school provide golfers with better turf grass, but it will also provide an environmentally friendly way to use a large volume of saline waste water.
Golf courses in the arid regions of U.S. Southwest use 750 billion gallons of fresh water a year for irrigation. Every gallon of fresh water that can be replaced by a treated gallon of waste water means one more gallon for human use or food production.
Few plants are able to survive in saline soil because of the process of osmosis, in which plants pull replacement water up through the roots and stalks.
Osmosis normally draws water from a point in the soil with abundant water to a point on the leaves lacking water, but in saline soil, salt attracts salt, which means salt in the soil pulls the saline water back out of the roots and into the earth.
A slightly saline tolerant plant is able to generate enough osmotic pull in mild saline conditions to draw that water up through the roots and survive, but the same plant in highly saline conditions won’t be able to pull water through the roots.
Breeding saline tolerant turf grass for golfers may seem frivolous, but it makes sense if golf courses could be irrigated with salt-laden waste water, said Rutgers plant breeder Stacy Bonos. Golf courses already using treated waste water for irrigation obtain it directly from municipal sewage treatment plants.
“We’re developing turf grasses that will thrive on waste water with an EC (electrical conductivity) of about three.”
This EC does not represent an extreme level of salinity, she added, but it’s a start.
“We mix the irrigation water to screen our plants at about three times stronger than our target for the final varieties,” she said.
“We mix to an EC of about 10. By comparison, sea water has an EC of about 55. The only plants allowed to move forward are those which survive overhead sprinkler irrigation with EC 10 water.”
Bonos said her project uses traditional plant breeding methods, and researchers are in the fourth and fifth cycle of screening the grasses. She said perennial rye grass is easy to work with because researchers can see the individual effect of what each parent plant passes on to the next generation.
Each generation of genes adds intensity to the trait for which they are selected, which is known as the additive effect. The visual distinction is strong enough that breeders can make their selection with the naked eye, although Bonos said they also used colour scans of a digital image.
“We found through a series of experiments that salt tolerance in perennial ryegrass is highly controlled by additive genetic effects,” she said.
“This is great news for breeders because we now know salt tolerance can be more easily bred for.”
Bonos and her team measured salt tolerance using visual percent green colour, which is the percentage of the plant that’s green and actively growing as compared to brown, which would indicate that it is dead or dying. Photographs of the plots clearly show which genetic strains thrive and which succumb to irrigation with EC10 water.
She said breeders don’t develop hybrids for turf grasses. Instead, they use a process called population improvement, which means seeds from her Rutgers project will be part of a variety mix designed for golf courses.
“We decided to use perennial rye grass because it has pretty good salt tolerance to begin with, compared to something like Kentucky blue grass,” she said.
“We’re also doing some fescues, although they’re not as promising.
“Perennial rye grass is a variety that’s already used a lot for over-seeding golf courses in the southern U.S. Many of these golf courses now are required to use effluent water, so there’s a demand for varieties like the ones we’re developing.
“We did more experiments to see how successfully genetic factors pass to the plant’s offspring. Two plants may combine to pass on tolerance, but one of those parents might not pass on that same strong influence if crossed with some other parent. This gives us a clue as to which parents are better to use in crosses and confirms what type of gene effects are influencing salinity tolerance.”
For more information, contact Bonos at firstname.lastname@example.org