Proline accumulation as a response to salt stress in 30 wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) cultivars differing in salt tolerance

The effects of NaCl salt (EC = 16 dS m⁻¹) on water potential, and accumulation of proline, Na⁺ and K⁺ in leaves on the main stem of 30 wheat cultivars (Triticum aestivum L.) at awn appearance and 20 days after anthesis (20 DAA) were evaluated in a greenhouse experiment. Plants were arranged in a according to a randomized complete block design with factorial treatments in three replications. Proline accumulation at 20 DAA increased with increasing salt stress. This increase was 27.4-fold with the salt-sensitive cultivar “Ghods,” while the mean was 5.2-fold for 19 salt-resistant cultivars. Positive correlations between proline, and K⁺ + Na⁺ concentrations associated with higher sensitivity to salt stress indicated that proline may not have a protecting role against salt stress. No correlation was observed between leaf proline and water potential. Almost no contribution to the osmotic adjustment seems to be made by proline. The contribution made by proline to the osmotic adjustment of plants at 20 DAA was 0.69 bar, whereas that made by K⁺ and Na⁺ was 2.11 and 4.48 bar, respectively. The 30 wheat CV_s used in this experiment showed different performances regarding the traits observed. Eleven of them showing the higher stress sensitivity indices had the highest level of proline and Na⁺ concentrations. They were considered to be salt-sensitive cultivars. Among the others, nine cultivars showed salt tolerance with almost the same Na⁺ and proline concentrations, but a higher K⁺/Na⁺ selectivity of ions from leaf to grains. In 10 of the cultivars, Na⁺ and proline concentrations were low, indicating the presence of a salt avoiding mechanism.     

基于分等成果的农用地综合生产能力

分析了农用地综合生产能力的内涵,阐述了农用地综合生产能力和生产潜力的理论体系,对不同层次的生产能力和生产潜力的核算方法进行了探讨。以东北地区为例,测算了区域农用地的生产能力和生产潜力,揭示其空间分布规律,并划定生产潜力区,为实现区域的耕地保护和粮食安全战略提供理论依据和技术支撑。     

淮北砂姜黑土区小麦单产变化及影响因素分析

砂姜黑土是黄淮海平原三大低产土壤之一,研究低产区粮食产量的影响因子,对于提高低产区的粮食生产具有重要意义。以阜阳地区为例,分析1949年以来淮北砂姜黑土区小麦单产、光温生产潜力及差距变化,运用灰色关联法分析小麦单产同各要素的关联度。结果表明,1970～2000年各因素的关联序依次为钾肥>复合肥>农机总动力>磷肥>氮肥>有效灌溉面积。钾肥是小麦单产的限制因子,农机总动力与小麦单产关系密切,氮、磷肥对小麦单产的影响下降,有效灌溉面积的关联序呈上升趋势。各要素对小麦单产的关联度均较高,但在不同阶段各要素的关联序也不同。最后提出淮北砂姜黑土区可持续发展的基本途径。     

低水势下土壤水分磁滞现象研究

Knowledge of the soil water characteristic curve is fundamental for understanding unsaturated soils. The objective of this work was to find scanning hysteresis loops of two fine textured soils at water potentials below wilting point. This was done by equilibration over NaCl solutions with water potentials of -6.6 to -18.8 MPa at 25 ℃. When cycled repeatedly through a series of potentials in the range noted previously both soils exhibited a hysteresis effect. The experimental differences in water content between the drying and wetting soils at the same water potential were much too large to be accounted for by failure to allow sufficient time to attain equilibrium as predicted by the exponential decay model. The wetting versus drying differences were relatively small, however, at only 4 mg g^-1 or less in absolute terms and about 3% of the mean of wetting and drying, in relative terms. Hysteresis should be a consideration when modeling biological and physical soil processes at water contents below the wilting point, where small differences in water content result in large potential energy changes.     

有机质去除对黄土纳米颗粒悬浮液稳定性的影响

土壤纳米颗粒是有机无机复合体,研究有机质对土壤纳米颗粒体系稳定性的影响具有重要意义。以塿土和褐土纳米颗粒以及去除有机质塿土和去除有机质褐土纳米颗粒为研究对象,分别测定颗粒的粒径分布、zeta电位、临界聚沉浓度(Critical coagulation concentration,CCC)等指标,利用德查金-朗道-维韦-奥弗比克(Derjauin-Landau-Verwey-Overbeek,DLVO)理论计算颗粒的哈默克(Hamaker)常数和相互作用能。结果表明:塿土和褐土纳米颗粒的平均直径分别为94.00nm和88.20 nm,去有机质黄土纳米颗粒的平均直径则略高于100 nm;相较于黄土纳米颗粒,去有机质黄土纳米颗粒的zeta电位绝对值降低,颗粒间静电排斥势能降低;DLVO模型拟合得到塿土和褐土纳米颗粒在真空中的哈默克常数分别为6.86×10^-20 J和9.73×10^-20 J,去有机质处理后相应数值为3.14×10^-20 J和3.40×10^-20 J,后者范德华引力势能降低;去有机质黄土纳米...     

冬季桃树生理生态指标变化规律研究

在分析空气温度、土壤水势以及土壤温度生态因子变化的基础上,研究了桃树茎干日变化规律以及冬季桃树的茎干变化。得出冬季土壤水势随时间逐渐减小,并受土壤温度变化影响。分析了冬季桃树地5、15和30 cm深度的土壤温度变化规律,并对曲线进行拟合,发现冬季土壤温度以二次函数规律变化,并且相关系数都在0.9以上。桃树茎干有明显的日变化规律,日最大收缩量受土壤水分状况影响较大,土壤水势高的处理,桃树茎干日最大收缩量大,相反水势较低的最大日收缩量变化较小。在2006年11月~2007年1月桃树茎干随时间不断收缩,但是收缩幅度与土壤水势有关,土壤水势高的收缩幅度较小,水势低的,收缩幅度较大。     

考虑灌溉及气候变化条件下葡萄花翅小卷蛾在中国的潜在地理分布

葡萄花翅小卷蛾Lobesia botrana(DenisSchiffermüller,1775)是我国重要的检疫性害虫,目前尚未传入我国,为了解该害虫在中国的潜在地理分布,根据该物种在全球已知的最新分布情况,利用CLIMEX 4.0.2在考虑灌溉条件的情景下,预测其在不同气候条件下的潜在地理分布。结果显示,葡萄花翅小卷蛾在我国的潜在地理分布范围较广,我国的主要葡萄产区均为葡萄花翅小卷蛾的适生区,且随着气候变化,至2030年,葡萄花翅小卷蛾在我国黑龙江、青海、四川省的部分适生区有所增加,适生程度也有所提高。因此应加强对葡萄花翅小卷蛾的检疫力度,防止其传入我国,保护我国葡萄种植业的生产安全。     

抗梅岭霉素和阿维菌素二斑叶螨种群生命力和繁殖力的研究

采用营养液培养的棉苗饲养二斑叶螨Tetranychus urticae Koch,用梅岭霉素、阿维菌素对其逐代进行抗性选育,至第9代,测定了两个抗性种群的抗性水平、生命力和繁殖力。结果表明:梅岭霉素抗性种群的抗性达7.9倍,其雌成螨寿命、产卵量、卵的孵化率和后代若螨成活率分别比对照增加54.08%、39.93%、6.57%和-15.44%。阿维菌素抗性种群的抗性达5.8倍,其雌成螨寿命、产卵量、卵的孵化率和后代若螨成活率分别比对照增加15.88%、10.87%、5.86%和-9.32%。由此发现梅岭霉素和阿维菌素对二斑叶螨的生长发育和繁殖有一定有利作用,抗性风险性较大,应引起重视。     

基于优化MaxEnt模型的疣果匙荠在中国的适生区预测与分析

本文优化了疣果匙荠分布数据筛选方式和MaxEnt软件参数设置,使用ENMTools剔除了冗余分布数据,调用R程序包Kuenm从1 240个不同参数组合的MaxEnt模型中筛选确定了最优参数.基于分布数据和参数优化的MaxEnt预测结果表明,疣果匙荠在中国的高度适生区和中度适生区分别占陆地总面积的9.4％和60.1％左右...     

潜在外来入侵甜菜孢囊线虫在中国的适生性风险分析

本文应用MAXENT与GARP两种生态位模型对甜菜孢囊线虫在中国的适生性进行了风险分析和预测。结果表明甜菜孢囊线虫可在中国17个省市生存,适生范围为26°N～48°N,77.6°E～136°E。甜菜孢囊线虫入侵的高风险区:内蒙古南部、新疆西部、河北中南部、山西东北部、宁夏、甘肃北部;中风险区:北京、天津、陕西、山西大部、内蒙古西部和东南部、吉林西部、新疆北部;低风险区:河南、陕西南部、山东、内蒙古中东部、新疆中部、辽宁、吉林大部、黑龙江南部、江苏、安徽、湖北、湖南、江西、浙江北部;而青海、新疆南部、西藏、四川、重庆、云南、贵州、广西、广东、福建、海南、内蒙古少数地区和黑龙江部分地区属于基本不发生区。我国内蒙古、新疆、辽宁等省市甜菜种植区均适合甜菜孢囊线虫发生,对上述地区的进出口岸应加强甜菜孢囊线虫的检疫工作。