Evolution and agriculture
进化和农业
Good catch
丰收
Some crops can absorb phosphorus from dust
有些作物能从尘土中吸收磷
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.
小麦是最早被驯化的植物之一，现在已经是非常普遍的农作物。所以，小麦还有很大的发展空间这种事情听起来似乎不太可能。然而，在人类和小麦建立联系的大概12000年之后，人们发现小麦做了一些不可思议的事情：当它的叶子被覆盖上一层沙尘时，它竟帮自己获得了所需的磷。
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.
我们所说的这株植物(或者更确切地说，多株植物)由以色列内盖夫本古里安大学的阿夫纳·格罗斯照料。格罗斯博士在今年12月上半月在线举行的美国地球物理联盟会议上说，他的研究受自己在犹太山的家乡尼夫沙洛姆附近徒步旅行时所启发。那会儿他经常注意到，植物的叶子被撒哈拉沙漠的沙尘暴带到那里的灰尘完全覆盖。
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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.
之后他想到，那些灰尘可能并不是一眼望去的那种阻挡光线的令人生厌的东西。相反，它们可能是有益的，因为灰尘里含有某些能够促进生长的元素，比方说磷。在此之前，植物学家一直认为落在植物上的灰尘中的磷并没有什么价值，因为它被锁在一种叫做磷灰石的不溶矿物中，无法被吸收。然而格罗斯博士推断，沙漠是大气中几乎所有自然产生的灰尘的来源，而那些生长在沙漠附近的植物很可能已经进化出了一种利用沙漠的方式，
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.
因此，他和他的两个同事，即同样在本古里安工作的苏迪普·蒂瓦里和吉莱特研究中心的拉恩·艾勒伊，开始用来自中东的农作物小麦和鹰嘴豆(世界上种植最多的农作物里排行17)这两个物种进行实验。此外，他们还种植了玉米作为对照，玉米是一种来自美洲的植物，在尘土较少的环境中进化而来。
First, having established them as seedlings, they starved their charges of phosphorus until signs of deficiency such as yellow leaves appeared. Then they scattered desert dust on the leaves of half of the specimens of each species, while taking steps to stop any of it reaching the soil. After this, though the dust-dosed maize continued to suffer from phosphorus deficiency, the wheat and chickpea plants perked up and grew to more than double the size of their undusted lab-mates. What is more, these species were clearly ready for the dust's arrival. As soon as a lack of phosphorus announced itself, two things happened. Their leaves became hairier, and therefore better at capturing dust. And those leaves also started secreting acid fluids that could dissolve any incoming apatite, assisting phosphorus's absorption.
首先，在培育出幼苗后，它们开始缺乏磷，直到出现黄叶等缺磷迹象。然后，他们把沙漠灰尘撒在每个物种一半标本的叶子上，同时采取措施阻止灰尘进入土壤。在这之后，尽管施了灰尘的玉米持续遭受缺磷的折磨，小麦和鹰嘴豆植株却活跃起来，长得比未施灰尘的同类植株大了两倍多。更重要的是，这些物种显然已经为尘埃的到来做好了准备。缺磷现象一旦发生，就会出现两种情况。它们的叶子变得多毛，因此捕捉灰尘的能力更强。这些叶子也开始分泌酸性液体，可以溶解任何进入的磷灰石，帮助磷的吸收。
That plants can take up phosphorus through their leaves is not, of itself, news to farmers—for this was established in the 1950s. But until now the practical consequence of such knowledge has been that crops are sprayed with liquid fertiliser derived, in turn, from apatite-containing rocks which have been treated with acid. Dusting leaves could, Dr Gross suggests, be an alternative and more efficient way of providing desert-derived crop species with the phosphorus they need. And maybe not just those. His next plan is to look at avocado and cocoa trees, which evolved in tropical regions of the Americas that regularly get a helpful transatlantic dose of Saharan dust carried westward by the trade winds. It will be interesting to see if they are up to the same tricks as wheat and chickpeas.
植物可以通过叶子吸收磷，这对农民来说并不是什么新鲜事儿，因为早在20世纪50年代这项研究就已经被确立。但到目前为止，这些知识的现实结果是，作物被喷洒液体肥料，反过来，这些肥料是在用酸处理过的含有磷灰石的岩石中提取出来的。格罗斯博士认为，用灰尘将叶子覆盖可能是另外一种更为有效的方式，它可以为沙漠作物提供所需的磷。或许不只是这样，他的下一个计划是研究鳄梨和可可树，它们生长在美洲的热带地区，这些地区经常受到信风带来的横跨大西洋的撒哈拉沙尘的影响。看看它们是否也在用和小麦、鹰嘴豆一样的伎俩，这会是件很有意思的事情。
来源：经济学人
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