A silk coating rich in bacteria allows seeds to better adapt to saline soil.

To feed a growing population, some researchers have come up with new ways to grow crops in saline fields. Scientists at the Massachusetts Institute of Technology (MIT), for example, have come up with a new technique based on suction-chip mulch that allows seeds to grow high lying in the soil. In addition to protecting seeds from salty soils, bacterial-treated silk coatings naturally provide symbiotic nitrogen fertilizer, enhancing the seed’s potential to germinate and grow.

A silk coating rich in bacteria allows seeds to better adapt to saline soil.

(From: MIT, via New Atlas)

In addition to protecting against salty soils, silk coatings are treated with bacteria that naturally produce nitrogen fertilizer, enhancing the seed’s potential to germinate and grow.

The new study is understood to be based on the school’s previous work of Professor of Civil and Environmental Engineering Benedetto Marelli, how to use a silk coating to extend the shelf life of grain crop seeds.

In the study, it was discovered that microorganisms can absorb nitrogen from the air and convert it into biofertilizers that can be used by plants. And this unique method of nitrogen fixation is natural all over the world.

The problem is that, although there is no actual shortage of such nitrogen-fixing bacteria, it is still difficult to preserve them in environments other than natural soils. Interestingly, silk is an excellent biological material.

The team, led by Marelli, decided to select one of the nitrogen-fixing bacteria for an in-depth study. By integrating this inter-root bacteria, which promotes plant growth, into the seed skin, it can be immediately restored to its original condition as soon as it is sown.

The initial test did not go as expected. Graduate student Augustine Zvinavashe then recommends adding seaweed sugar, a sugar that some organisms depend on for survival in low-water environments, to the mixture.

To cover the coating, the researchers suspended silk, bacteria and seaweed sugar in water and immersed the seeds in a solution for a few seconds.

Subsequent studies have shown that specially treated seeds do develop better than the normal control group and can successfully germinate on previously uncultivated land.

What’s more, this immersion or spraying process is simple and affordable, and can be achieved at normal ambient temperatures and air pressure. It means that small and medium-sized farmers can be easily handled.

The researchers say the silk they use is water-soluble. Once exposed to the soil, the bacteria can be released. In soils where salinity may hinder its normal growth, the coating also provides the protection and nutrients needed for seed germination.

For now, the team’s research is still focused on symbiotic root tumors that fix nitrogen fertilizer for legume crops, but are also actively exploring the possibility of pairing other crops. One potential way is to genetically modify bacteria, or to integrate the DNA of bacteria into plants.

The future of this technology is rather promising, even if it is eventually used only on high-salinating soils. Details of the study will be published this week in the journal PNAS.

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