Agriculture and evolution – Wheat absorbs phosphorus from desert dust | Science & technology

W.THA HEAT among the first domestically produced plants and is now the most widespread crop in the world. So it looks like there wouldn’t be much left to learn about what works. However, about 12,000 years after the beginning of human relations with wheat, a wheat plant was caught doing something unexpected. He helped himself to a much-needed dose of phosphorus when its leaves were covered with desert dust.

That plant (or, rather, plants) was in the care of Avner Gross of Ben Gurion University in the Negev, Israel. As Dr. Gross reported at this year’s meeting of the American Geophysical Union of America, which took place online in the first half of December, his study was inspired by visits he took near Neve Shalom, the his hometown in the Judean Mountains. On those, he would often notice the leaves of plants completely covered in dust carried there by sandstorms from the Sahara desert.

It so happened that this dust may not have been the slightest hint at first sight. On the other hand, it may be beneficial because of its growth-enhancing elements such as phosphorus. Until then, botanists had accepted that phosphorus in landfills was of little value because it is trapped in an indissoluble mineral called apatite. This makes it unavailable for inclusion. But Dr. Gross reasoned that plants that had grown near deserts, where almost all the naturally occurring dust in the atmosphere, may have used a method to exploit it. .

So he and two colleagues, Sudeep Tiwari, also at Ben Gurion, and Ran Erel of the Gilat Research Center, started experimenting with a pair of species, wheat and chickpeas (the 17th largest crop planted). in the world), that both of them came from the Middle East. As a control, they also picked up a makeup, an American plant that thrived in a much less dusty environment.

First, after they were established as seeds, they halted their phosphorus costs until signs of deficiency appeared such as yellow leaves. They then spread desert dust on the leaves of half the samples of each species, taking steps to prevent any of it from reaching the soil. After this, even though the wheat germ was suffering from phosphorus deficiency, the wheat and chickpea plants grew and grew to more than twice the size of the undigested lab companions. Moreover, it was clear that these species were ready for the coming of the dust. As soon as the lack of phosphorus declared itself, two things happened. Their leaves became softer, so they better trap dust. And these leaves also began to evaporate acidic liquids that any incoming apatite could release, helping to absorb phosphorus.

It is not news to farmers that plants can take phosphorus through their leaves – as this was established in the 1950s. But so far the practical result of that experience has been that crops are sprayed with liquid fertilizers that come, therefore, from rocks containing acid-treated apatite. Dust leaves, Dr. Gross suggests, could be an alternative and more effective way of providing much-needed phosphorus to desert-based crop species. And maybe not just those. His next plan is to look at avocado and cocoa trees, which originated in tropical regions of America that regularly receive a helpful transatlantic dose of Sahara dust carried west by the trade winds. . It will be interesting to see if they are up to the same tricks as wheat and chickpeas.

This article appeared in the Science & Technology section of the print edition under the heading “Good catch”

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