Greatly enhanced arsenic shoot assimilation in rice leads to elevated grain levels compared to wheat and barley
Greatly enhanced arsenic shoot assimilation in rice leads to elevated grain levels compared to wheat and barley
复制标题
DOI：
10.1021/es070627i
复制
发表时间：
2007-10-01
影响因子：
11.4
通讯作者：
Meharg, Andrew A.
中科院分区：
文献类型：
--
作者：
Williams, Paul N.;Villada, Antia;Meharg, Andrew A.
对173个单独的商业化种植的温带水稻，小麦和大麦的样本集的籽粒，地上部和土壤进行了调查，以调查砷（As）的同化和转运的变化。稻米样品来自Carmargue（法国）、Donana（西班牙）、加迪斯（西班牙）、加州和阿肯色州。小麦和大麦是从康沃尔郡和德文郡（英格兰）以及苏格兰东海岸采集的。从土壤中转移到粮食是一个数量级的水稻比小麦和大麦，尽管较低的率拍摄到粮食转移。水稻籽粒砷含量超过0.60 μ g g（-1）d。wt被发现在水稻土中生长的水稻只有约10亩g-1的As，表明水稻土中的As是有问题的粮食As水平。这是由于水稻的茎/土比率很高，接近0.8，而大麦和小麦分别为0.2和0.1。这些转移率的差异可能是由于厌氧水稻土相比，大麦和小麦的好氧土壤中As的形态和动态的差异。在水稻中，出口的作为从地上部的粮食似乎是在严格的生理控制下的粮食/地上部的比例下降了一个数量级以上（从类似的0.3至0.003毫克/公斤），并作为作为在地上部的水平增加从1至20毫克/公斤。小麦和大麦的茎向籽粒输出可能发生下调，但在本次调查中未发现茎As水平。英格兰西南部的一些农业土壤中的含量超过200微克/天。wt，尽管小麦和大麦的谷物水平从未突破0.55 μ g g（-1）d。重量这些粮食水平实现了水稻在土壤中的一个数量级较低的As。因此，在人类食物链中的风险，需要考虑在厌氧VS有氧生态系统的背景下。
Paired grain, shoot, and soil of 173 individual sample sets of commercially farmed temperate rice, wheat, and barley were surveyed to investigate variation in the assimilation and translocation of arsenic (As). Rice samples were obtained from the Carmargue (France), Donana (Spain), Cadiz (Spain), California, and Arkansas. Wheat and barley were collected from Cornwall and Devon(England) and the east coast of Scotland. Transfer of As from soil to grain was an order of magnitude greater in rice than for wheat and barley, despite lower rates of shoot-to-grain transfer. Rice grain As levels over 0.60 mu g g(-1) d. wt were found in rice grown in paddy soil of around only 10 mu g g-1 As, showing that As in paddy soils is problematic with respect to grain As levels. This is due to the high shoot/soil ratio of similar to 0.8 for rice compared to 0.2 and 0.1 for barley and wheat, respectively. The differences in these transfer ratios are probably due to differences in As speciation and dynamics in anaerobic rice soils compared to aerobic soils for barley and wheat. In rice, the export of As from the shoot to the grain appears to be under tight physiological control as the grain/shoot ratio decreases by more than an order of magnitude (from similar to 0.3 to 0.003 mg/kg) and as As levels in the shoots increase from 1 to 20 mg/kg. A down regulation of shoot-to-grain export may occur in wheat and barley, but it was not detected at the shoot As levels found in this survey. Some agricultural soils in southwestern England had levels in excess of 200 mu g g(-1) d. wt, although the grain levels for wheat and barley never breached 0.55 mu g g(-1) d. wt. These grain levels were achieved in rice in soils with an order of magnitude lower As. Thus the risk posed by As in the human foodchain needs to be considered in the context of anaerobic verses aerobic ecosystems.