外源硫对镉胁迫下马齿苋光合性状和矿质元素吸收的影响

从光合反应系统揭示外源硫(S)诱导马齿苋镉(Cd)耐受性的生理机制,为外源S缓解重金属毒害提供理论依据.采用营养液培养,研究外源S供体(NH4)2SO4对100 mg/L Cd胁迫下马齿苋叶片光合色素、光合特性、叶绿素荧光参数和矿质营养元素的影响.结果表明,Cd胁迫可显著降低马齿苋叶片中叶绿素a和叶绿素b含量;净光合速率、蒸腾速率、气孔导度均显著降低,而胞间二氧化碳浓度上升,表明非气孔因素是Cd胁迫诱导马齿苋光合抑制的主要因素;同时,PSⅡ实际光化学效率(ФPSII)、电子传递效率(J)、化学猝灭系数(qP)显著下降,而非化学猝灭系数(qN)显著上升,表明Cd胁迫影响马齿苋PSⅡ反应系统的正常运行.外施400 mg/L(NH4)2SO4显著提高马齿苋叶片叶绿素a含量、叶绿素b含量和叶绿素a/b比值,增强马齿苋叶片光合作用和PSⅡ原初光化学反应量子效率.对5种与光反应系统密切相关的矿质元素含量进行分析发现,Cd处理显著增加马齿苋叶片中的Ca和Fe含量,显著抑制马齿苋对Mg、Mn和Cu的吸收.Cd胁迫下马齿苋叶片的变黄与Mg、Mn的亏缺有关,而与Fe缺乏无关;添加外源S可显著提升马齿苋叶片中Ca、Mg、Fe、Cu和Mn含量,从而增强Cd胁迫下马齿苋叶片的PSII反应系统功能.     

矿质元素对阳春砂植株生长发育的影响

通过箱式砂砾培养法,对阳春砂（Amomum villosum Lour.）进行不同营养条件的栽培实验,研究氮、磷、钾、钙、硼、锌6种不同矿质元素丰缺时对植株生长发育的影响。结果显示,在6种不同的矿质元素中,当氮为15.0 mmol/L、磷1.0 mmol/L、钾6.0 mmol/L、钙0.5 mmol/L、锌8.0 × 10⁻⁵ mmol/L、硼0.46 mmol/L时,能满足阳春砂植株基本的生长与发育;10.0 mmol/L的磷、8.0 × 10⁻³ mmol/L的锌以及0.46 mmol/L的硼,可促进植株的生长发育;而施用50.0 mmol/L的氮、6.0 × 10² mmol/L的钾以及50.0 mmol/L的钙时,则会对植株的生长发育产生极大的毒害作用。因此阳春砂植株生长与发育过程中矿质元素应合理施用。     

保水剂结合矿质元素对水稻幼苗生长发育的影响

水稻种子萌发过程中,保水剂促进淀粉转化为可溶性糖,不同浓度的保水剂对淀粉转化的促进作用没有显著差异;保水剂能提高种子呼吸强度,且存在浓度差异。矿质元素对水稻幼苗生长发育具有促进作用,Ｓｉ和Ｍｏ明显促进幼苗生长和根系发育,Ｃｕ有利于叶片生长和根系分化。保水剂结合矿质元素能进一步提高各种矿质元素的相应作用。     

气候变化背景下秦岭地区陆地生态系统水分利用率变化趋势

为探究未来气候变化背景下秦岭地区陆地生态系统水分利用率(WUE)的变化规律及其对气候变化的响应,结合IPCC第五次报告资料中心的CCSM4、GISS-E-R、GISS-E-H、IPSL-CM5R-LR-CM、Nor ESM1-1-ME等5个模型相关模拟结果,预测和分析秦岭地区2006—2100年在RCP2.6、RCP4.5、RCP6.0和RCP8.5 4种未来典型气候变化情景下其水分利用率的变化趋势及其与降雨、气温、CO_2浓度等关键气候变化因子之间的关系。研究结果表明:4种未来情景下预测的秦岭地区生态系统WUE几乎全为正距平,各情景下WUE倾向率为0.0136—0.13 g C kg-1H_2O 10a-1,均达到极显著水平,且随辐射强迫增加,WUE距平值与倾向率也相应增加。各情景下GPP的增长趋势强于ET,使得两者的比值(即WUE)呈现增长趋势,并随辐射强迫的增加,两者的差异愈发显著,即WUE增长随辐射强迫的增强而更显著。同时,各模型预测的年均气温倾向率为0.21—0.498℃/10a,降雨量倾向率为7.78—17.66 mm/10a。由于气温、降雨量、CO2等关键气候变化因子调控GPP正增长速率大于ET,以及生态系统LAI值和自身的植被演替过程直接影响生态系统WUE,最终使得生态系统WUE呈正增长趋势。其中GPP的显著增加是未来秦岭地区生态系统WUE增长的直接因素,而气温的显著增加与大气CO_2浓度的升高则是WUE变化的主要环境因素,降雨量的影响相对较弱。     

外源Spd对盐碱胁迫下番茄幼苗氮代谢及主要矿质元素含量的影响

采用水培方法,研究了盐碱与Spd处理对两品种番茄(中杂9号和金棚朝冠)幼苗氮代谢及主要矿质元素含量的影响.结果表明:盐碱胁迫下,番茄幼苗干生物量显著减少,植株生长受到抑制;叶片和根系硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)活性及硝态氮(NO3--N)、全N、全K、Ca2+、Mg2+含量显著降低,铵态氮(NH4+-N)、Na+含量显著增加;两品种叶片及中杂9号根系谷氨酸脱氢酶(GDH)活性显著升高,金棚朝冠根系GDH活性变化不显著;叶片全P含量显著降低,根系全P含量显著升高(金棚朝冠)或无显著变化(中杂9号).Spd处理通过增强NR、GS、GOGAT活性提高了植株对NH4+的同化利用率,有效缓解了盐碱胁迫导致的氮代谢紊乱,进而促进不同器官对P、K、Ca、Mg、Na的吸收、释放或转运,在一定程度上维持了各元素之间的相对平衡,从而增强植株对逆境的适应能力.此外,盐碱对中杂9号的抑制作用及外源Spd对其氮代谢紊乱和营养失衡的缓解作用高于金棚朝冠.     

外源Spd对盐碱胁迫下番茄幼苗氮代谢及主要矿质元素含量的影响

采用水培方法,研究了盐碱与Spd处理对两品种番茄（中杂9号和金棚朝冠）幼苗氮代谢及主要矿质元素含量的影响.结果表明： 盐碱胁迫下,番茄幼苗干生物量显著减少,植株生长受到抑制;叶片和根系硝酸还原酶（NR）、谷氨酰胺合成酶（GS）、谷氨酸合成酶（GOGAT）活性及硝态氮（NO₃^--N）、全N、全K、Ca²⁺、Mg²⁺含量显著降低,铵态氮（NH₄⁺-N）、Na⁺含量显著增加;两品种叶片及中杂9号根系谷氨酸脱氢酶（GDH）活性显著升高,金棚朝冠根系GDH活性变化不显著;叶片全P含量显著降低,根系全P含量显著升高（金棚朝冠）或无显著变化（中杂9号）.Spd处理通过增强NR、GS、GOGAT活性提高了植株对NH₄⁺的同化利用率,有效缓解了盐碱胁迫导致的氮代谢紊乱,进而促进不同器官对P、K、Ca、Mg、Na的吸收、释放或转运,在一定程度上维持了各元素之间的相对平衡,从而增强植株对逆境的适应能力.此外,盐碱对中杂9号的抑制作用及外源Spd对其氮代谢紊乱和营养失衡的缓解作用高于金棚朝冠.     

矿质元素互作及重金属污染的研究进展

随着工农业的发展,重金属污染问题在我国越来越严重。矿质元素互作的研究是理解重金属植物体内迁移规律,解决矿质营养利用和重金属污染治理的矛盾以及重金属复合污染问题的必然要求。本文从几个与重金属关系密切的矿质元素入手,并结合离子组学的发展,简要介绍了矿质元素与重金属的互作方面的主要进展,并对解决重金属污染和重金属复合污染问题进行了探讨。     

矿质元素对毛头鬼伞菌丝体生长的影响

研究了4种矿质元素对栽培食用菌毛头鬼伞菌丝体生长的影响。4种矿质单元素添加试验结果表明,能使毛头鬼伞菌丝体旺盛生长的最佳浓度分别是CaCl20.1 mmol/L、MgSO48 mmol/L、KCl 1.22 mmol/L、NaH2PO413 mmol/L。4种元素协同作用试验结果表明,单元素浓度的最佳生长量与混合施用时的最佳生长量一致。以毛头鬼伞的主要栽培料之一的棉子壳估算,原料中的4种矿质元素浓度均偏低,必须补充矿质元素才能满足毛头鬼伞菌丝体的旺盛生长。     

陆地生态系统植物多样性对矿质元素输入的响应

人类活动的加剧改变了陆地生态系统矿质元素(如氮、磷、钾等)循环的速度和方向,并且对生态系统的结构和功能也产生重要影响。如今,矿质元素输入量的改变及其产生的后续效应对陆地生态系统生物多样性的影响备受学者们的关注。从4个方面综述了全球氮沉降背景下主要矿质元素输入的改变对陆地植物多样性的影响及其机理:1)矿质营养元素限制的概念、确定方法以及与植物多样性的耦合关系;2)概述了氮、磷、钾等主要矿质元素输入对陆地植物多样性的影响:主要表现为负面效应;3)探讨了矿质元素输入影响植物多样性的可能机制,包括生态系统水平上的机制(如竞争排斥、酸化铝毒、物种入侵、同质性假说,间接诱导机制等)和植物个体水平上的机制(如元素失衡和环境敏感性增加等);4)根据目前研究现状,指出了已有研究的局限性,分析了未来可能的研究方向和重点。     

The role of grasslands in food security and climate change

Background

Grasslands are a major part of the global ecosystem, covering 37 % of the earth''s terrestrial area. For a variety of reasons, mostly related to overgrazing and the resulting problems of soil erosion and weed encroachment, many of the world''s natural grasslands are in poor condition and showing signs of degradation. This review examines their contribution to global food supply and to combating climate change.

Scope

Grasslands make a significant contribution to food security through providing part of the feed requirements of ruminants used for meat and milk production. Globally, this is more important in food energy terms than pig meat and poultry meat. Grasslands are considered to have the potential to play a key role in greenhouse gas mitigation, particularly in terms of global carbon storage and further carbon sequestration. It is estimated that grazing land management and pasture improvement (e.g. through managing grazing intensity, improved productivity, etc) have a global technical mitigation potential of almost 1·5 Gt CO₂ equivalent in 2030, with additional mitigation possible from restoration of degraded lands. Milk and meat production from grassland systems in temperate regions has similar emissions of carbon dioxide per kilogram of product as mixed farming systems in temperate regions, and, if carbon sinks in grasslands are taken into account, grassland-based production systems can be as efficient as high-input systems from a greenhouse gas perspective.

Conclusions

Grasslands are important for global food supply, contributing to ruminant milk and meat production. Extra food will need to come from the world''s existing agricultural land base (including grasslands) as the total area of agricultural land has remained static since 1991. Ruminants are efficient converters of grass into humanly edible energy and protein and grassland-based food production can produce food with a comparable carbon footprint as mixed systems. Grasslands are a very important store of carbon, and they are continuing to sequester carbon with considerable potential to increase this further. Grassland adaptation to climate change will be variable, with possible increases or decreases in productivity and increases or decreases in soil carbon stores.     

Agriculture under Climate Change in China: Mitigate the Risks by Grasping the Emerging Opportunities

ABSTRACT

There have been increasing concerns on risks and uncertainty posed by climate change to China's future crop production. The existing assessments using popular process-based and site-specific crop growing models highlight the significant extent of climate-induced yield reduction, and thus suggest a scary downward risk for China's future food production. Surprisingly, much less attention has been paid to exploring the potential gains that may also be brought by climate change. To address this imbalance, we develop an integrated agro-climatic and ecological assessment tool that is capable of detecting the shifts of multicropping opportunities under different climate change scenarios. The application of this tool to the context of China reveals significant extension of multicropping opportunities brought in by climate change. We argue for an active adaptation to such emerging opportunities through both market and policy incentives, because the aggregate gain of such adaptation is sufficient to outweigh the loss as revealed by the existing assessments.     

全球气候变化与粮食安全——2012年Planet Under Pressure国际会议述评

\"Planet Under Pressure 2012——NEW KNOWLEDGE TOWARDS SOLUTIONS\"会议于2012年3月26日至3月29日在英国首都伦敦召开,来自全球100多个国家和地区的科学家共同讨论减轻地球压力的新方法,为6月将要举办的Rio+20可持续发展大会提供科学的理念和建议。会上,粮食安全方面的相关研究主要探讨了气候变化、城市化、全球化、人口增长、疾病、食物消费结构、经济发展水平等因素对粮食安全的影响,并讨论了全球气候变化条件下实现粮食安全的可能的途径,诸如扩大高产农用地面积、发展以农户为基本单位的农业、推行基因农业、提高农业信息化水平、制定合理的政策等。会议表现出三大特点:(1)多尺度、多领域信息的充分交流;(2)提出了绿色经济、绿色发展等新的科学理念;(3)强调科学和政策的结合。四个方面的启示:(1)加强各学科的结合,不断开拓新的研究领域,提出新的研究思路;(2)全面考虑,将理论和实际有效结合;(3)增强政府与科学家的沟通与交流;(4)拓展国际视野,加强全球方面的研究,提高参与全球活动的主动性和积极性。     

Food security and climate change: on the potential to adapt global crop production by active selection to rising atmospheric carbon dioxide

Agricultural production is under increasing pressure by global anthropogenic changes, including rising population, diversion of cereals to biofuels, increased protein demands and climatic extremes. Because of the immediate and dynamic nature of these changes, adaptation measures are urgently needed to ensure both the stability and continued increase of the global food supply. Although potential adaption options often consider regional or sectoral variations of existing risk management (e.g. earlier planting dates, choice of crop), there may be a global-centric strategy for increasing productivity. In spite of the recognition that atmospheric carbon dioxide (CO(2)) is an essential plant resource that has increased globally by approximately 25 per cent since 1959, efforts to increase the biological conversion of atmospheric CO(2) to stimulate seed yield through crop selection is not generally recognized as an effective adaptation measure. In this review, we challenge that viewpoint through an assessment of existing studies on CO(2) and intraspecific variability to illustrate the potential biological basis for differential plant response among crop lines and demonstrate that while technical hurdles remain, active selection and breeding for CO(2) responsiveness among cereal varieties may provide one of the simplest and direct strategies for increasing global yields and maintaining food security with anthropogenic change.