Ligands involved in Pb immobilization and transport in lettuce,radish, tomato and Italian ryegrass

Lead (Pb) and other heavy metals represent a great source of concern in agriculture because they may disperse from polluted sources and accumulate in crop organs. This research study was performed with three edible crops and one pasture species (lettuce: Lactuca sativa L. cv. Romana; radish: Raphanus sativus L. var. radicicola; tomato: Lycopersicon lycopersicum L. Karst.; Italian ryegrass: Lolium multiflorum Lam). It was aimed at (1) assessing how species affect Pb distribution among plant organs, (2) determining the extent to which Pb is localized in edible organs, and (3) ascertaining whether it could be possible to distinguish which compounds are responsible for the transport of Pb from one plant organ to another and which compounds are responsible for the accumulation of this metal inside each plant organ. The experiment was conducted in the greenhouse. Plants were grown in plastic pots using a Pb‐spiked sandy soil as substrate. Total Pb concentrations in different plant organs and in soil were determined. Within plants, the maximum accumulation of Pb was found in roots while the remaining part of Pb was mainly located in leaves. Pb L_III edge XANES (X‐ray Absorption Near Edge Spectroscopy) was applied to identify the principal Pb carrier molecules in the different plant organs. The data suggest that in roots Pb immobilization is mainly due to the complexing ability of histidine, which binds the metal and, to a lesser extent, to precipitation of Pb as carbonate. The transport to the upper plant organs is mainly attributed to Pb complexes with organic acids. In stems and leaves, Pb bonding is mainly carboxylic and amino acid‐like, thus confirming the role of these substances in promoting Pb mobility. Thio amino acidic (glutathione and cysteine‐like) Pb complexes, which in this study were only found in stems, can also be held responsible for Pb long‐distance transport from roots to shoots.     

基于IRIV算法优选大豆叶片高光谱特征波长变量估测SPAD值

在植物叶绿素特征波长变量筛选过程中,与叶绿素关系较弱的波长变量极易被忽略,导致这些弱信息变量包含叶绿素的有效信息丢失,因此,确定叶片光谱中弱信息变量对揭示叶绿素高光谱响应规律具有重要意义。该研究以江汉平原大豆鼓粒期的叶片为研究对象,采集80组大豆叶片高光谱和SPAD(soil and plant analyzer development)值,分析SPAD值与大豆叶片反射率相关关系和光谱波长变量自相关关系,基于迭代和保留信息变量法(iteratively retains informative variables,IRIV)筛选大豆叶片的特征波长变量,建立偏最小二乘回归(partial least squares regression,PLSR)和支持向量机(support vector machine,SVM)模型估测SPAD值。结果表明,大豆叶片SPAD值与光谱反射率在可见光波段具有极显著负相关,在近红外波段存在不显著的正相关性(P0.01);可见光、近红外2波段的波长变量之间相关性较弱,但2波段内变量之间的相关性较强;基于IRIV算法确定了大豆叶绿素的特征波长变量,利用特征波长变量建立的估测模型的估测能力高于仅利用强信息波长变量建立的估测模型,表明弱信息变量对估测叶片SPAD值具有重要意义;IRIV-SVM模型估测能力最优,验证集R2和相对分析误差(RPD)分别为0.73、1.82。该文尝试证明了光谱中弱信息变量的重要性,为揭示叶片高光谱响应机理提供了理论依据。     

薏苡脱壳机关键部件作业参数优化与试验

针对薏苡脱壳设备脱净率差、破碎率高,相关工艺与装备研究几近空白的现状,该文结合薏苡物料特性,运用中心组合试验设计理论开展关键部件作业参数试验与优化,重点研究薏苡脱壳机脱壳仓作业关键参数中动盘转速、动静磨盘间隙、静盘工作面宽度对脱净率、破碎率的影响规律,并以脱净率、破碎率为响应指标进行多目标优化。首先对主产区主要薏苡品种物料特性进行研究,并进行与脱壳相关的物理参数测定,然后采用二次正交旋转组合试验方法设计试验并用Design-Expert进行数据处理,建立脱净率、破碎率的回归数学模型并进行方差分析。分析得出影响薏苡脱壳机脱净率的主次因素依次为:动盘转速静盘工作面宽度动静磨盘间隙;影响破碎率的主次因素依次为:静盘工作面宽度动静磨盘间隙动盘转速。通过响应曲面方法分析各因素交互作用对脱净率、破碎率的影响,并根据优化目标的重要程度(脱净率较破碎率重要)对回归模型进行多目标优化,得出薏苡脱壳机关键部件最佳作业参数组合为:动盘转速1 076.02 r/min,动静磨盘间隙4.91 mm,静盘工作面宽度7.63 mm。此时,脱壳机脱净率最高、破碎率最低,其值分别为50.49%、3.02%。将优化参数在薏苡脱壳设备上开展验证及批量化流水加工作业,流水加工作业脱净率达51.1%、破碎率3.6%,设备作业质量大幅提升,达到了较为理想的效果。该研究可为提升薏苡脱壳机作业质量提供参考。     

分子标记鉴定蔬菜作物种子纯度的研究进展

综述了国内外关于分子标记鉴定蔬菜作物种子纯度的研究现状及蔬菜种子纯度分子标记鉴定法的商业应用基础，指出了今后应进一步开展以降低成本为核心的分子标记技术体系标准化研究。     

云南河口地区2007/2008年冬春低温与热带作物寒害

通过对2007/2008年冬春河口地区热带作物受寒害调研,总结了河口地区低温寒害时空分布规律,提出了主要热带作物寒害的防御对策。     

基于微根管技术的玉米根系生长监测

为了研究玉米根系生长规律,该文利用固城农业气象试验站内设置的大型根剖面系统,采用微根管观测法,对试验地上玉米主要生育期的根系生长动态进行定期直接跟踪监测,并以方形整段标本法作为参照标准,对试验数据采用MATLAB软件辅助图像处理和现代统计方法进行分析。结果表明：微根管法与方形整段标本法对得出的根长密度随深度增加呈递减型有较好的一致性,两者相关系数达到0.83以上,通过0.05的显著性检验;由观测数据建立的回归方程能较好地反映土壤中玉米根系生长规律,进一步表明微根管法是一种破坏性较小、可准确定位跟踪植物根系在土壤中生长动态变化的先进技术,对植物根系生长研究有较好的推广应用价值。     

A Framing Analysis of Newspaper Coverage of Genetically Modified Crops in Kenya

There was much public debate in Kenya about genetically modified (GM) crops when the national Biosafety Bill went through the parliamentary process toward enactment into law. This study analyzed how GM crops were framed in three mainstream Kenyan newspapers—the Daily Nation, The Standard, and Taifa Leo—during the period. The agriculture frame was predominant in the Daily Nation and The Standard, while the safety and regulation frames dominated coverage in Taifa Leo. Only 34.7% of articles were neutral in tone. Scientists and government officials, who generally spoke in favor of GM crops, were the most frequently quoted sources. Recommendations to improve the quality of coverage include training of journalists to ensure objective and balanced reporting.     

山西主要农作物生产过程中影响农业机械适用性因素分析

山西省南北狭长,气候及地理环境状况差异较大,用于农作物生产的农业机械适用性也存在很大差异,对主要农作物的生产模式以及对机械作业的影响因素进行分析,旨在进一步加快山西省的农机化进程。     

<Emphasis Type="Italic">Pandanus amaryllifolius</Emphasis> Roxb. cultivated as a spice in coastal regions of India

Pandanus amaryllifolius, an herb, is cultivated in home gardens in coastal regions of India. The leaves are added to ordinary rice while cooking to impart basmati rice aroma. The plant bears the same aroma principle 2-acetyl-1-pyrroline (2AP) that has been reported in Basmati and other scented rice. Quantitatively the 2AP contents are highest in this plant among the plant kingdom. Therefore, it has good scope for commercial cultivation.