Evolution and agriculture
Some crops can absorb phosphorus from dust
Wheat was among the first plants to be domesticated and is now the most widespread crop in the world. It thus sounds unlikely there would be much left to learn about what makes it thrive. Yet, some 12,000 years after relations between people and wheat began, a wheat plant has been caught doing something unexpected. It helped itself to a dose of much-needed phosphorus when its leaves received a coating of desert dust.
The plant(or, rather, plants)in question were in the care of Avner Gross of the Ben Gurion University of the Negev, in Israel. As Dr Gross told this year's meeting of the American Geophysical Union, which took place online during the first half of December, his study was prompted by hikes he had taken near Neve Shalom, his home village in the Judean Hills. On these, he often noticed plant leaves completely covered in dust that had been carried there by sand storms from the Sahara desert.
It occurred to him that this dust might not be the light-blocking nuisance it appeared at first sight. It could, on the contrary, be beneficial because of the growth-enhancing elements such as phosphorus which it contained. Until then, botanists had assumed that phosphorus in dust landing on a plant was of little value, because it is locked up in an insoluble mineral called apatite. This makes it unavailable for absorption. Dr Gross, however, reasoned that plants which had evolved near deserts, the source of almost all naturally occurring dust in the atmosphere, might well have evolved a way to exploitit.
He and two colleagues, Sudeep Tiwari, also at Ben Gurion, and Ran Erel of the Gilat Research Centre, therefore started experimenting with a pair of species, wheat and chickpeas (the world's 17th most planted crop), that both came originally from the Middle East. As a control, they also raised some maize, a plant from the Americas that evolved in farless dusty surroundings.