Reconstructing the paleotopography beneath the loess cover with the aid of an electromagnetic induction sensor

During the last glacial period (Weichselian), wind-blown loess was deposited over the undulating landscape of central Belgium, which had been formed in surfacing Tertiary marine sediments. Since valleys were filled up with a thicker loess layer than hill tops, the present topography is much smoother. This smoothing was enhanced by subsequent erosion processes. Reconstructing the paleolandscape at a detailed scale is almost impossible by conventional procedures based on soil augerings. Therefore, the use of the electromagnetic induction sensor, EM38DD, was evaluated as an alternative for mapping the depth to the Tertiary clay substrate. On our 2.7 ha study site, located in the loess belt of central Belgium, a strong non-linear relationship (R² = 0.86) was found between the apparent electrical conductivity (ECa), measured by the vertical dipole orientation of the EM38DD and the depth to a Tertiary clay substrate. These predictions were validated by independent observations of the depth to the Tertiary clay and a correlation coefficient of 0.83, with an average error of 0.22 m, was found. So, our dense ECa measurements (2 by 2 m resolution) allowed us to build a three-dimensionall surface of the depth to the Tertiary substrate, reconstructing the paleotopography beneath the loess cover. This paleotopography revealed distinct erosion patterns on the surface of the Tertiary clay. The continuity of these was confirmed by an analysis of surface flow patterns conducted on the reconstructed paleotopography. The non-invasive, time- and cost-effective electromagnetic induction sensor was found to offer new perspectives to reconstruct and analyse in detail the Quaternary paleotopography beneath the loess cover.     

西北地区光伏电站植被恢复模式研究综述

[目的]分析当前西北地区光伏电站现有的植被恢复模式,提出一种光伏电站内增加植被覆盖的生态恢复节水型新模式,为西北地区光伏电站的综合利用提供科学理论基础。[方法]广泛查阅近几年国内外的文献,对西北地区光伏电站植被恢复的有利条件、现有的西北地区光伏电站植被恢复模式的特点等进行总结、分析,并对今后研究方向进行探讨。[结果]当前西北地区光伏电站植被恢复研究还处在起步阶段,并未充分考虑水资源的合理高效利用和光伏电站的独特性。[结论]要重点探索"西北地区光伏电站内水—光—热的再分配规律"这一生态和光伏电站领域相交叉的重要科学问题,加强光伏电站植被恢复的多学科融合,并对光伏电站生态系统进行实时监测,制定严格的光伏电站环境影响评价标准等。     

普通小麦体细胞无性系R2代变异发生特点

小麦Ｒ２代体细胞无性系变异存在４种发生方式，即合株性稳定谱异，全株分离变异，穗系嵌合稳定变异，穗系嵌合分离变异，其中稳定变异相当普遍、红占总变异的１／３。发生阶段较全株性变异于发生较迟的穗系嵌合变异。不同的变异性状有不同折发生方式。株型、穗型、芒型和叶色变异多为分离变异，熟期为稳定变异，株高，腊质等兼有稳定及分离变异，其中某性状是显性突变的结果，多数分离性状的分离均属简单分离，且箐少见到基因突变的     

耕作方式转变对土壤蓄水保墒影响的RZWQM模型模拟

基于2011—2012年和2013—2014年河南禹州冬小麦长期定位试验,利用传统耕作、免耕和深松处理下土壤水分、地上部生物量和产量对RZWQM(Root zone water quality model)模型进行率定和验证,然后利用率定后的模型模拟传统耕作转变为保护性耕作方式后0~100 cm土层贮水量、耗水量、土壤剖面水分平衡及水分利用效率的动态变化。在模型率定和验证中,土壤分层含水率模拟值和实测值之间的均方根误差(RMSE)分别在0.009~0.025 cm3/cm3和0.005~0.054 cm3/cm3范围内变化。模型模拟结果表明RZWQM模型能够较好地模拟耕作方式转变后土壤分层水分的动态变化,4种不同耕作转变模式(传统耕作分别转变为免耕、免耕+秸秆覆盖、深松、深松+秸秆覆盖)下,传统耕作转变为免耕后产量最高,水分利用效率最大,达19.3 kg/(hm2·mm)。因此,该模拟条件下传统耕作转变为免耕的蓄水保墒效果最好。     

马尾松体细胞胚胎发生相关基因PmSERKl的克隆与表达分析

体细胞胚胎发生不仅是植物微繁、种质保存的有效手段,同时也是研究高等植物胚胎发育和遗传转化的模式系统之一。本研究从马尾松未成熟合子胚诱导的胚性细胞团中成功克隆了体胚发生受体激酶基因PmSERK1。该基因全长2303bp,包含完整的开放阅读框,编码626个氨基酸,其蛋白分子量约为69kD。序列分析发现PmSERK1与其它植物的SERK基因高度同源。系统进化树重建表明,PmSERK1与已知参与体胚发生的关键SERK基因聚为一类,如MtSERK1、CuSERK1、AtSERK,和DcSERK。表达分析显示：PmSERK1在主要的组织器官（根、茎、针叶等）略有表达;但在诱导培养的非胚性愈伤中没有检测到表达,而在经继代培养的胚性愈伤中表达很高且逐渐增加,且在培养20d时达到最高。另外,在再生的子叶胚中,PmSERK1的表达量也很高。综上所述表明,PmSERK1是与体胚发生相关的关键SERK基因的直系同源基因,可以作为愈伤组织胚性的标记基因。     

苦瓜转录因子McEIL2的克隆及其表达分析

本研究从已构建的苦瓜果实均一化文库筛选得到一个EIN3-like同源EST序列,结合RACE技术,克隆得到EIN3基因c DNA全长序列,命名为Mc EIL2(Gen Bank登录号:KF595122)。该基因全长2 122 bp,开放阅读框1 890 bp,编码629个氨基酸,预测该蛋白的分子量为71.58 k D,与黄瓜Cus EIN3、甜瓜Cm EIL1、苜蓿Mt EIL1、绿豆Vr EIL1和番茄Le EIL1的蛋白同源性分别为89.61%、78.37%、71.23%、69.09%和65.66%。Mc EIL2基因的编码蛋白亚细胞定位于细胞核,荧光定量分析表明Mc EIL2基因表达量在幼果期先强后弱,绿熟期最低,破色期表达量大幅增加至最高随后下降,推测该基因参与苦瓜果实成熟软化调控过程。本研究初步明确了Mc EIL2基因在苦瓜成熟过程表达模式,可为今后进一步揭示苦瓜果实成熟软化的分子机制奠定基础。     

Bt基因在不同陆地棉基因型的表达研究

研究了Bt基因在陆地棉不同遗传背景下的表达差异。结果表明,(1)Bt基因在不同陆地棉基因型中均能充分表达,与常规(非抗虫)棉相比抗虫性极为显著。(2)不同陆地棉基因型品系(种)之间抗虫性比较,有差异且部分品系间达极显著水平。(3)Bt基因在不同陆地棉基因型的表达,前期(对二代棉铃虫的抗性)差异较大;中期(对三代棉铃虫的抗性)差异变小;后期(对四代棉铃虫的抗性)没有显著差异。(4)转Bt基因抗虫棉Bt基因的表达随棉花的生育进程呈逐渐降低趋势,即对二代棉铃虫的抗性>对三代棉铃虫的抗性>对四代棉铃虫的抗性。     

小麦雄性不育系保持系过氧化物酶同工酶的比较研究

从小麦雄性不育系、保持系的10个不同组织、器官中共检测出8种过氧化物酶,在叶、芽鞘、根、节、节间、穗轴、叶鞘和芒中,不育系和保持系的过氧化物酶基本相同,说明这种酶由细胞核编码,但在花粉粒发育的3个不同时期,不育系与保持系间的过氧化物酶有明显差异,表现为不育系中的过氧化物酶同工酶多于保持系,这可能是由于不育系中细胞质不育基因对核基因的表达有调控作用,这种调控作用表现为不育细胞质基因的去阻遏作用,即不育细胞质基因可以去除细胞核中编码过氧化物酶基因的阻遏作用,使不育系中有更多的过氧化物酶基因得以表达,造成不育系中过氧化物酶同工酶多于保持系的现象.     

Irrigation Water Management for Efficient Water Use in Mulched Onion

Caused by the necessarily imperfect seed placement accuracy of sowing machines and, additionally, caused by many other biotic and abiotic factors, the resulting plant stands exhibit nonregular spatial distributions of its plants. Based on several simplifying assumptions, a stochastic approach is developed which allows an estimation of the effects of nonregular spatial patterns on yield per area. In this approach, two random variables are attached to each plant: single plant yield E and individual space A . The latter is estimated by the area of Thiessen polygons. Yield per area, calculated by the expectation of the ratio E/A , can be approximately expressed dependent on the means ( Ē and Ā ) and coefficients of variation ( v _E and v _A ) of E and A and their correlation ( r _EA ). In relation to the commonly used estimate Ē/Ā for yield per area, one obtains yield decreases if v _A / v _E  <  r _EA . This inequality, however, will be usually valid in the field of applications. The theoretical approaches and results were applied to three experimental data sets for drilled seeds of winter oilseed rape ( Brassica napus L.) (plant density: 60 plants m⁻², row distance: 10 cm). These data sets are characterized by different accuracies of longitudinal distributions within rows (58 %, 101 %, 150 %): yield depression increases with an increasing variability of plant distances within rows.     

主要禾谷类作物DGAT基因家族比较分析

二酰甘油酰基转移酶（DGAT）是三酰甘油合成的限速酶,在植物油脂合成中发挥重要作用。为明确禾谷类作物DGAT基因家族的表达特征,利用已知DGAT成员序列对主要禾谷类作物进行全基因组扫描,分析其亚型差异及表达特点。结果表明,DGAT蛋白具有高脂肪、碱性和不稳定性。系统发育树中DGAT成员聚类为4个亚族,不同亚族成员间平行进化。DGAT基因结构具有组内保守性和组间多样性,基序存在多种类型,不同亚型成员具有特异的结构域组成。DGAT上游序列中,存在植株发育和胁迫响应等多种类型顺式作用元件,说明DGAT广泛参与不同生物学过程。转录组分析结果显示,DGAT广泛存在于不同组织中。在遭遇干旱和低温等不同非生物胁迫时,DGAT受到不同程度诱导,具有时空表达差异性。本研究可为禾谷类作物DGAT基因家族成员功能研究奠定基础。