Alfalfa helped to overcome salty soil threat

Scientists in Utah found using salt-tolerant bacteria as an inoculant helped improve the crop’s yield in tough conditions

Researchers in Utah might have found a way to help crops that are suffering from salty soils.

Brigham Young University scientists used salt-tolerant bacteria to inoculate alfalfa affected by salty soil, finding the inoculant improved the crop’s yield.

“This was in a controlled environment in the lab and the greenhouse, but we saw routinely at least 50 percent improvement,” said Brent Nielsen, who led the project and is a professor of microbiology and molecular biology at the university.

“It’s not making it just as good if no salt is there, but we’re getting 50 to 60 percent of that level.”

Nielsen said the researchers trialed alfalfa because it’s a popular crop in Utah and is easily affected by salinity.

He suggested the findings could potentially lead to commercial development of such inoculants, helping producers dealing with high salinity in their fields.

“There are still some big questions to make it practical to farmers,” he said, noting several companies are doing more with inoculants that contain endophyte bacteria.

“There is quite a field of endophyte research and applications, but from what I know there hasn’t been a lot of attention to salinity, so this opens up a new direction. Maybe we could do the same thing with salinity.”

To do the study, researchers collected roots of salt-tolerant plants and ground them up. From there, they grew bacteria from it in a petri-dish.

During that process, the team isolated more than 40 different bacteria isolates, some of which are able to tolerate ocean-level saltiness.

The researchers then applied the bacteria isolates through a solution, testing alfalfa’s ability to grow in salty conditions in the lab and in a greenhouse at the Institute for Advanced Learning and Research in Virginia.

They used one percent sodium chloride, an amount that’s enough to significantly inhibit un-inoculated plants.

“We grew plants either with or without the inoculation of the different isolates, and with or without the presence of salt,” Nielsen said.

After inoculating the plants with the isolates, he said they found two isolates (Halomonas and Bacillus) that considerably stimulated growth in alfalfa that was in salt.

He said the findings are significant for countries around the world where soils are becoming saltier.

“Forty percent or more of cultivated land around the world is affected by salinity,” he said.

In the southwestern United States, for example, farmers use irrigation that contains small amounts of salt. Overtime, the salinity builds and negatively affects their yield, Nielsen said.

“Some areas are experiencing reduction in crop yield, and especially in a lot of vegetables we eat, which are sensitive to salt,” he said. “The main thing they are seeing is higher salinity, so it’s really causing an impact and will continue to cause an impact in areas that irrigate.”

He said their next step is to carry out field trials on the inoculated crops.

As well, they have begun lab and greenhouse experiments on rice, green beans and lettuce.

The research was published online in Frontiers in Microbiology.

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