| 叶施L-半胱氨酸对水稻镉和矿质元素含量的影响 |
| 摘要点击 5946 全文点击 682 投稿时间：2021-01-11 修订日期：2021-02-05 |
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| 中文关键词 水稻 镉 L-半胱氨酸(L-Cys) 叶面喷施 矿质元素 |
| 英文关键词 rice cadmium L-cysteine (L-Cys) foliar application mineral element |
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| 中文摘要 |
| 为评估将L-半胱氨酸（L-Cys）作为水稻降Cd叶面调理剂的可行性，通过湖南的田间试验，采用小区试验法研究了L-Cys对水稻籽粒中Cd和矿质元素含量的影响，并通过检测水稻各营养器官的Cd分布和Cd赋存形态的变化，探究了L-Cys调控水稻籽粒Cd积累的作用机制.结果表明，在开花期叶面喷施一次L-Cys即可使水稻籽粒Cd含量显著降低，同时提高其Mg和K的含量，对Ca、Mn和Zn的含量无显著影响.L-Cys的降Cd效果随喷施浓度增加而增强，当浓度为10 mmol·L-1时，籽粒中Cd含量降至我国食品安全标准0.2 mg·kg-1以内，降幅达59.2%，同时显著降低了水稻营养器官穗轴、第一节、穗颈、旗叶、第二节间、第二节、第二叶、基部茎叶和根中的Cd含量，降幅分别为58.3%、56.0%、62.7%、67.0%、59.3%、61.5%、60.2%、54.9%和50.3%.水稻不同部位间的Cd转移因子显示，第一节是水稻营养体拦截有害元素Cd的关键器官.叶面喷施L-Cys提高了Cd从旗叶到第一节和第二节间到第一节的转移因子，增幅最高达105.4%和45.8%，并抑制了Cd从第一节继续向上到穗颈的转运，降幅最高达27.5%.在水稻第一节中，L-Cys处理同时降低了无机态、水溶态和残渣态Cd的含量，并提高了其中残渣态Cd的比例至94.4%.由此可见，叶面喷施L-Cys能够降低水稻各营养器官Cd积累量，并促进水稻中Cd向第一节的转运及其对Cd的固定作用，进而提高关键器官第一节对Cd的拦截能力，最终显著抑制Cd向籽粒中的转运积累，同时，叶面喷施L-Cys不降低水稻籽粒中矿质营养元素的含量，具有较好的应用前景. |
| 英文摘要 |
| To evaluate the feasibility of applying L-cysteine (L-Cys) as a foliar conditioner for Cd reduction in rice, a field experiment was conducted to investigate the concentration of Cd and mineral elements in rice after the foliar application of L-Cys. The variation in Cd distribution and morphology in key rice organs was examined to study the Cd reduction mechanisms of spraying L-Cys on rice. The results showed that foliar application of L-Cys at the rice-flowering stage significantly decreased Cd concentration in grains, in a concentration dependent manner, without inhibiting the accumulation of mineral elements Ca, Mg, K, Mn, and Zn. With a 10 mmol ·L-1 L-Cys application, Cd concentration in rice grains decreased by 59.2%, to below 0.2 mg ·kg-1, which is the maximum safety limit in China. Foliar application of L-Cys also inhibited Cd accumulation in rice vegetative organs, including rachises, first nodes, neck-panicles, flag leaves, second internodes, second nodes, second leaves, stalks, and roots (58.3%, 56.0%, 62.7%, 67.0%, 59.3%, 61.5%, 60.2%, 54.9%, and 50.3%, respectively). After transfer factor calculation, first nodes were found to be the key organ for Cd blocking in rice. The application of L-Cys increased Cd transfer from flag leaves and second internodes to first nodes (105.4% and 45.8%, respectively), but decreased Cd transfer from first nodes up to neck-panicles (27.5%). In rice first nodes, the concentrations of Cd in the inorganic, water soluble, and residue states were all lower following L-Cys application, and the proportion of residual Cd increased to 94.4%. Therefore, foliar application of L-Cys significantly inhibited Cd transport and accumulation in rice grains, by decreasing the Cd concentrations of various vegetative organs and improving Cd interception in the first nodes. This is a promising way to produce rice with lower Cd concentrations and normal mineral element concentrations in Cd-contaminated paddy fields. |
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