Silken Promise: Scientists Hack Seeds to Grow in Salty Soils

Published on January 3rd 2020
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Soil teeming with friendly organisms and nourishing nutrients is an important ingredient of life. And in the interests of food security, the availability of such arable land is essential.
As discussed in recent Candide articles, the world's soil has a complexity sometimes forgotten about amid the excitement and toil of plant preparation.
But the health of a resource sometimes taken for granted has major impacts beyond what we grow in our gardens; beyond the food on our farms even.
Tragically, some 24 billion tons of fertile soil is lost every year, according to the UN-supported Global Land Outlook.
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Either through erosion, desertification, flooding or man-made consequences like careless fertilizing, irrigation and overcropping, a valuable resource is destroyed.
It means tackling poor quality or redundant soil is something that requires urgency.
Enter what could be an important solution to soil degradation - a way to hack salty earth with soluble silk.

Problem soils

More than 1.3 billion people are currently relying on nutrient barren, inhospitable soils to eke out an existence.
In a 2015 study, Cornell University researchers explored the link between chronic poverty and depleted soils.
It suggested intervention methods such as micronutrient-fortified fertilizers and subsidizing farming products as a way to improve crop growth.
Problem soils are something the United Nations University Institute for Water has also highlighted, advocating for ways to remediate salt-affected earth hampering development in places like China, Iran, Thailand and North Africa.

Silky seeds

Scientists at the Massachusetts Institute of Technology (MIT) have now come up with a game-changing answer to problem soils: silk-covered seeds. It's not quite a silver bullet soil solution.
However, it is an inventive way to work in salinated earth, which can be an unintended by-product of irrigation.
Researchers found that by covering seeds in a mixture of silk, trehalose sugar, and rhizobacteria, germinating plants can receive a natural fertilizer-generating boost.
The discovery means that in the future seeds could be engineered to yield a plethora of different crops in poor, highly salinated soils.
Outlining the research team’s work, MIT explained how suspending chickpea seeds in a silk mixture provided the seeds with a protective coating in soils where they were likely to perish.
“When I was doing some research… I stumbled on biofertilizers that can be used to increase the amount of nutrients in the soil,” said researcher Benedetto Marelli, MIT professor of civil and environmental engineering, explaining the birth of the idea.
From there Marelli and the MIT team experimented with silkworm cocoons after realizing the protein fibre can preserve biological material, like nitrogen-fixing bacteria needed for plant growth.
Treating the seeds with rhizobacteria, another plant growth support, and trehalose, which can help plants through periods of dryness, allowed the enhanced seeds to naturally produce nitrogen fertilizer amid salty soil.
According to Marelli, the silk mix “is water-soluble, so as soon as it’s exposed to the soil, the bacteria are released.”

Future of farming?

After tweaking the formula with trehalose, tests with the seeds were carried out at MIT and a research facility operated by the Mohammed VI Polytechnic University in Ben Guerir, Morocco.
It yielded positive results that could be beneficial for future farmers. The experimental seeds were growing “in soil where otherwise nothing grows,” Augustine Zvinavashe, one of the paper’s authors, said in a statement.
“The process is fast, easy, and it might be scalable” for larger farm holdings, Zvinavashe said. Another advantage is that the technique is a speedy one, he added. “The seeds can be simply dip-coated for a few seconds.”
The group expects to test more seeds outside of lab controlled conditions in Morocco soon.
To improve their crop strengthening technique, the researchers also plan to create new coatings that not only protects seeds from saline soil but also makes them more resistant to drought conditions.
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