Heavy metal pollution seriously threatens global rice production and food security.Arbuscular mycorrhizal fungi(AMF)can alleviate heavy metal stress in rice.To summarize existing research and propose new research dire...Heavy metal pollution seriously threatens global rice production and food security.Arbuscular mycorrhizal fungi(AMF)can alleviate heavy metal stress in rice.To summarize existing research and propose new research directions,this review outlines the current status of heavy metal pollution from perspectives including general pollution situation,soil heavy metal pollution,water heavy metal pollution,and paddy field heavy metal pollution.This paper also synthesizes the negative impacts of heavy metal stress on rice growth in terms of morphological indicators,photosynthesis,redox balance,and nutritional metabolism.It also analyzes the mechanisms by which AMF alleviate heavy metal stress in rice,induding physiological as and biochemical regulatory mechanisms,as well as molecular and genetic regulatory mechanisms.Furthermore,this paper provides research perspectives regarding integration with genetic engineering and breeding technologies,applications under combined stress conditions,and technological integration with field application promotion,aiming to establish a theoretical foundation for further research in ecological restoration and safe utilization of heavy metal-contaminated paddy fields.展开更多
为适应护理专业化发展需求,突破高级实践护士(advanced practice nurses,APN)培养中的标准不一、临床实践不足等瓶颈,笔者所在医院自2023年起与北京大学护理学院合作,构建并实施了“一二三四”培养模式,即以高级实践护士核心能力为中心...为适应护理专业化发展需求,突破高级实践护士(advanced practice nurses,APN)培养中的标准不一、临床实践不足等瓶颈,笔者所在医院自2023年起与北京大学护理学院合作,构建并实施了“一二三四”培养模式,即以高级实践护士核心能力为中心,依托院校双导师制,通过三大课程模块与“观摩-协管-主管-主导”四阶临床实践路径,对30名护士进行APN系统化培养。实践表明,该模式有效提升了护士的临床决策、专科护理与科研能力,带动了科室护理质量与患者满意度改善。文章分享了该模式的关键做法与实施体会,旨在为医院开展APN培养提供实践参考。展开更多
The rice-wheat rotation in southern China is characterized by frequent flooding-draining water regime and heavy nitrogen(N)fertilization. There is a substantial lack of studies into the behavior of dissolved organic n...The rice-wheat rotation in southern China is characterized by frequent flooding-draining water regime and heavy nitrogen(N)fertilization. There is a substantial lack of studies into the behavior of dissolved organic nitrogen(DON) in the intensively managed agroecosystem. A 3-year in situ field experiment was conducted to determine DON leaching and its seasonal and yearly variations as affected by fertilization, irrigation and precipitation over 6 consecutive rice/wheat seasons. Under the conventional N practice(300kg N ha-1for rice and 200 kg N ha-1for wheat), the seasonal average DON concentrations in leachate(100 cm soil depth) for the three rice and wheat seasons were 0.6–1.1 and 0.1–2.3 mg N L-1, respectively. The cumulative DON leaching was estimated to be1.1–2.3 kg N ha-1for the rice seasons and 0.01–1.3 kg N ha-1for the wheat seasons, with an annual total of 1.1–3.6 kg N ha-1. In the rice seasons, N fertilizer had little effect(P > 0.05) on DON leaching; precipitation and irrigation imported 3.6–9.1 kg N ha-1of DON, which may thus conceal the fertilization effect on DON. In the wheat seasons, N fertilization had a positive effect(P < 0.01)on DON. Nevertheless, this promotive effect was strongly influenced by variable precipitation, which also carried 1.8–2.9 kg N ha-1of DON into fields. Despite a very small proportion to chemical N applied and large variations driven by water regime, DON leaching is necessarily involved in the integrated field N budget in the rice-wheat rotation due to its relatively greater amount compared to other natural ecosystems.展开更多
A laboratory-based aerobic incubation was conducted to investigate nitrogen （N） isotopic fractionation related to nitrification in five agricultural soils after application of ammonium sulfate （（NH4）2804）. The s...A laboratory-based aerobic incubation was conducted to investigate nitrogen （N） isotopic fractionation related to nitrification in five agricultural soils after application of ammonium sulfate （（NH4）2804）. The soil samples were collected from a subtropical barren land soil derived from granite （RGB）, three subtropical upland soils derived from granite （RQU）, Quaternary red earth （RGU）, Quaternary Xiashu loess （YQU） and a temperate upland soil generated from alluvial deposit （FAU）. The five soils varied in nitrification potential, being in the order of FAU 〉 YQU 〉 RGU 〉 RQU 〉 RGB. Significant N isotopic fractionation accompanied nitrification of NH4＋. 615N values of NH4＋ increased with enhanced nitrification over time in the four upland soils with NH4＋ addition, while those of NO3 decreased consistently to the minimum and thereafter increased. 515N values of NH4＋ showed a significantly negative linear relationship with NH4＋-N concentration, but a positive linear relationship with NO3-N concentration. The apparent isotopic fractionation factor calculated based on the loss of NH4＋ was 1.036 for RQU, 1.022 for RGU, 1.016 for YQU, and 1.020 for FAU, respectively. Zero- and first-order reaction kinetics seemed to have their limitations in describing the nitrification process affected by NH4＋ input in the studied soils. In contrast, N kinetic isotope fractionation was closely related to the nitrifying activity, and might serve as an alternative tool for estimating the nitrification capacity of agricultural soils.展开更多
文摘Heavy metal pollution seriously threatens global rice production and food security.Arbuscular mycorrhizal fungi(AMF)can alleviate heavy metal stress in rice.To summarize existing research and propose new research directions,this review outlines the current status of heavy metal pollution from perspectives including general pollution situation,soil heavy metal pollution,water heavy metal pollution,and paddy field heavy metal pollution.This paper also synthesizes the negative impacts of heavy metal stress on rice growth in terms of morphological indicators,photosynthesis,redox balance,and nutritional metabolism.It also analyzes the mechanisms by which AMF alleviate heavy metal stress in rice,induding physiological as and biochemical regulatory mechanisms,as well as molecular and genetic regulatory mechanisms.Furthermore,this paper provides research perspectives regarding integration with genetic engineering and breeding technologies,applications under combined stress conditions,and technological integration with field application promotion,aiming to establish a theoretical foundation for further research in ecological restoration and safe utilization of heavy metal-contaminated paddy fields.
文摘为适应护理专业化发展需求,突破高级实践护士(advanced practice nurses,APN)培养中的标准不一、临床实践不足等瓶颈,笔者所在医院自2023年起与北京大学护理学院合作,构建并实施了“一二三四”培养模式,即以高级实践护士核心能力为中心,依托院校双导师制,通过三大课程模块与“观摩-协管-主管-主导”四阶临床实践路径,对30名护士进行APN系统化培养。实践表明,该模式有效提升了护士的临床决策、专科护理与科研能力,带动了科室护理质量与患者满意度改善。文章分享了该模式的关键做法与实施体会,旨在为医院开展APN培养提供实践参考。
基金supported by the Jiangsu Provincial Natural Science Foundation of China(No.BK-2010612)the Foundation of State Key Laboratory of Soil and Sustainable Agriculture,China(No.Y05-2010034)the National Natural Science Foundation of China(No.41001147)
文摘The rice-wheat rotation in southern China is characterized by frequent flooding-draining water regime and heavy nitrogen(N)fertilization. There is a substantial lack of studies into the behavior of dissolved organic nitrogen(DON) in the intensively managed agroecosystem. A 3-year in situ field experiment was conducted to determine DON leaching and its seasonal and yearly variations as affected by fertilization, irrigation and precipitation over 6 consecutive rice/wheat seasons. Under the conventional N practice(300kg N ha-1for rice and 200 kg N ha-1for wheat), the seasonal average DON concentrations in leachate(100 cm soil depth) for the three rice and wheat seasons were 0.6–1.1 and 0.1–2.3 mg N L-1, respectively. The cumulative DON leaching was estimated to be1.1–2.3 kg N ha-1for the rice seasons and 0.01–1.3 kg N ha-1for the wheat seasons, with an annual total of 1.1–3.6 kg N ha-1. In the rice seasons, N fertilizer had little effect(P > 0.05) on DON leaching; precipitation and irrigation imported 3.6–9.1 kg N ha-1of DON, which may thus conceal the fertilization effect on DON. In the wheat seasons, N fertilization had a positive effect(P < 0.01)on DON. Nevertheless, this promotive effect was strongly influenced by variable precipitation, which also carried 1.8–2.9 kg N ha-1of DON into fields. Despite a very small proportion to chemical N applied and large variations driven by water regime, DON leaching is necessarily involved in the integrated field N budget in the rice-wheat rotation due to its relatively greater amount compared to other natural ecosystems.
基金Supported by the Natural Science Foundation of Jiangsu Province,China(No.BK2010612)the Foundation of State Key Laboratory of Soil and Sustainable Agriculture(No.Y052010034)the Knowledge Innovation Program of the Institute of Soil Science,Chinese Academy of Sciences(No.ISSASIP0723)
文摘A laboratory-based aerobic incubation was conducted to investigate nitrogen （N） isotopic fractionation related to nitrification in five agricultural soils after application of ammonium sulfate （（NH4）2804）. The soil samples were collected from a subtropical barren land soil derived from granite （RGB）, three subtropical upland soils derived from granite （RQU）, Quaternary red earth （RGU）, Quaternary Xiashu loess （YQU） and a temperate upland soil generated from alluvial deposit （FAU）. The five soils varied in nitrification potential, being in the order of FAU 〉 YQU 〉 RGU 〉 RQU 〉 RGB. Significant N isotopic fractionation accompanied nitrification of NH4＋. 615N values of NH4＋ increased with enhanced nitrification over time in the four upland soils with NH4＋ addition, while those of NO3 decreased consistently to the minimum and thereafter increased. 515N values of NH4＋ showed a significantly negative linear relationship with NH4＋-N concentration, but a positive linear relationship with NO3-N concentration. The apparent isotopic fractionation factor calculated based on the loss of NH4＋ was 1.036 for RQU, 1.022 for RGU, 1.016 for YQU, and 1.020 for FAU, respectively. Zero- and first-order reaction kinetics seemed to have their limitations in describing the nitrification process affected by NH4＋ input in the studied soils. In contrast, N kinetic isotope fractionation was closely related to the nitrifying activity, and might serve as an alternative tool for estimating the nitrification capacity of agricultural soils.
