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Nutrient-Producing Silk Coats Can Help Seeds Germinate in Unfavourable Conditions

Research by the Massachusetts Institute of Technology (MIT) found that coasting seeds with the right materials may help agriculture in land with little agricultural value.

Needing the right type of soil might be a thing of the past with this new coating developed by a team of engineers from MIT. The coat is also treated with a kind of bacteria that is able to naturally produce a nitrogen fertilizer that is essential in germinating plants. Tests also demonstrated the coated seeds could grow well in soils conditions with high salinity.

The findings are being published in the journal PNAS, in a paper by graduate students Augustine Zvinavashe and Hui Sun, post doctorate Eugen Lim, and professor of civil and environmental engineering Benedetto Marelli.

This research stemmed from Marelli’s previous work on silk coatings for extension of shelf life of seeds used as food crops. “When I was doing some research on that, I stumbled on biofertilizers that can be used to increase the amount of nutrients in the soil,” he says. These fertilizers use microbes that live symbiotically with certain plants and convert nitrogen from the air into a form that can be readily taken up by the plants.

Providing a natural fertilizer in this way can also help to overcome current problems associated with artificial fertilizers. These include the environmental impact on soil quality. Using the silk coating the team was able to preserve the biological material and tried it out on nitrogen-fixing bacterial known as rhizobacteria.

“We came up with the idea to use them in our seed coating, and once the seed was in the soil, they would resuscitate,” he says. Preliminary tests did not turn out well, however; the bacteria weren’t preserved as well as expected.

Trehalose, a type of sugar was also added to the mix which some organisms use to survive under low-water conditions. With all three components – silk, nitrogen-fixing bacteria, and trehalose – were suspended in water, the researchers soaked the seeds in the solution for a few seconds to allow even coating.

The resulting plants were able to develop in healthier than those from untreated seeds with the help of the natural fertilizer production by the bacteria. These plants grew successfully in soil from fields that are presently not suited for agriculture.

The research team will be conducting further tests on the coatings to develop them to be more resistant to drought and begin testing of the current seed coats in open experimental fields in Morocco next year. [APBN]